gdax does have 2 prices.
see their charts.. red and green bid and ask buy and sell

ignore values in screenshot. its an old image from google search i used as example. but on the left you can see there is a 29cent difference between the buy and sell

new hampshire project tried it. (google search can explain the rest of the story)

the buy is always higher.

if it was the other way round people would buy and instantly sell for guaranteed profit. no one would ever lose

trading works by you buying at a price and waiting for the overall value to increase, whereby the new price would allow you to sell.
EG
day 1: buy:16640.45. sell price 16460.20
day 2: buy:16940.45. sell price 16760.20

buy 1btc on day1 and sell it on day2 = $119.75 profit

that said most FX platforms are not actually trading real bitcoins but just playing around with a database they own with numbers they input.
if you cannot deposit or withdraw bitcoins and your only able to deposit and withdraw fiat while only 'playing' with a cough btc cough price on their platform. stay away from it. its not real

its like boiler room gambling on racehorses without actually buying a ticket
its like boiler room gambling on stocks/shares without actually buying a certificate

the real cause of this is much more simpler then people think. and surprisingly its not actually bitcoin related

many banks do not care about bitcoin.
here is the thing, FIAT does not get burned/vanish when a transfer occurs. it just moves from one persons account to another persons account. bitcoin does NOT destroy fiat, so banks dont care about the conomic impact of bitcoin. its irrelevant to them

what they do care about is if the recipient of the funds has had flag warnings related to chargebacks.

yes thats right, scammers who send money to coinbase, get their bitcoins and withdraw bitcoins, then call up their banks and claim "theft" to try getting a chargeback (wire reversal)

and its the amount of wire reversal claims that these banks then flag coinbase and others as high risk.
this has happened alot. even individual coin sellers on localbitcoins have been victim to this even without ever touching coinbase or informing their bank the use of the funds. the banks flag them as high risk due to chargeback scammers claiming the 'service' scammed them. when infact is the claimer thats doing the scammer, and thus it then effects others who know the recipient is innocent but the banks treat the recipient as a high risk

what will happen is new regulation that only BANKS can create cryptos and any other non bank will get done for counterfeiting and such.

plus it will be smartcontracts, like lightning where people deposit funds into a smart contract so the counterparty has dual control of th funds. thus its not going to be permissionless.. many numbskulls dont realise that lightning IS banking due to smart contracts with a hub/counterparty control

lastly because banks will have access to the funds its not that much different in regards to customer 'ownership' of funds than traditional banking systems.. the only real benefit is to the banks by not needing as much security/auditing personnel.. i see little to no benefit for bank customers for a bank using crypto.

in short. getting excited that a bank makes their own crypto is the opposite to a revolution.
but hey, all im ever gonna read is people shouting "this will cause price rise due to a media coverage and speculation"

you defense is that it cost you only $20 in fee's... but..... you still had to wait hours, and at laggy times even longer.

i think you need to re-assess yourself if you think that even $20 is acceptable.
imagine if you bought something in a shop. and the retailer said thats $10.. you hand them a $100 and they say they will give you back $70 in 2-5 hours.

wake up. the dev's behind core have lost all recognition of what bitcoins 2009-2014 ethos was, they are sellouts and have done stupid crap to ruin bitcoin not make it better

and the only rebuttal i ever here is "but the price is rising so good investment, never use it to buy things just hodl" (facepalm)

anyway, on topic
the UK banking system ALREADY for decades now has a banking system that lets people wire transfer funds instantly FOR FREE.. its called "faster payments" only a few lazy second rate banks put a un-needed delay/fee's on wire transfers

this is what happens when core puts code in to deliberately ban nodes that are not core. it opens the floodgate of alts. and centralises code control more in favour of core

if core left it for the orphaning mechanism (consensus) to function. then the script kiddies would actually need to re-code alot more, and thus less altcoins would occur.

but now we have this centralised system where the only time the bitcoin network upgrades, is if core have controlled it.

but hey no one cares about decentralisation, they just care about free coins and a false presence of decentralisation which is actually just distribution

'decentralisation is dead, long live coin distribution'

or the protocol starts measuring in 100byte/sat instead of 1byte/sat
lame brain developers think the protocol cant go below 1byte/sat without having to add millisat units if measure. but they are wrong. it can be done, if they really thought about it.

also a new fee priority formulae could be added that actually works.

bitcoin has LOST its utility appeal. and only has its investment appeal left.

however litecoin with its lower fee's and ability to be used for household transactions has given it the perception of being better than bitcoin.
though many think 'bitcoin cash' bitcoin gold and other bitcoin offshoots dominate.. they all lack the main thing.. utility.

if things like bitpay and coinbases merchant shopping cart api's were to take on a new coin. that coin would surpass all others in the utility perception. and right now it looks like litecoin is getting close to that

nope its done by nodes.

pools collate the data into batches. but the nodes validate and accept/reject it

its not mining hashrate

for instance imagine you owned a pool with DOUBLE the hashrate of the entire network. but your codebase of your pool node wanted to change a rule..
all that will happen is that your blocks will get rejected by the network because their desired rules are not your rules.
you could mine billions of blocks but only you would retain them and everyone else would reject them. thus  you have made your own altcoin that only you hold

consensus is about the NODES that accept the rules. hash power has nothing to do with the RULES. the hashpower is only about protecting the DATA from people manipulating the data retrospectively. EG for someone to make a block that does not contain certain transactions (attempted refund) from a block in 2012. then that pool needs to also recreate every block after that to get uptodate to todays blockheight. and the rules must match to not get rejected.

in short hashrate does not determine the rules. it just makes changing old data harder

---

the politics of CORE controlling the rules.. is the thing people are avoiding talking about. because its core that set the rules and push people to download their wallet as oppose to other wallets. thus they control the development and they control the rules. and yes they do and have bribed big names to get their way. (many free all inclusive weekend breaks, jobs, bonuses, freebies and more)

# bitcoin payment is anoymous pseudonymous
# bitcoin is decentralized distributed
# bitcoin is not issued by any
# nobody core can increase total supply of

1.many scammers have had their funds traced via the blockchain. examples are the agents that investigated silkroad got arrested because it was found out the agents themselves were taking funds out of silk road,.. also the mtgox funds are known. and other funds can be traced. so its not anonymous. its pseudonymous. for instance it took me 0.5 seconds to find out catmony owns 1CzctPaiivoMJLwTCEVQZvzLWWtbfP7ENo

2. the data is distributed. but there is a centralised hub that CONTROLS what the rules should be.. its known as core. there have been too many instances that the control of the bips(proposals) and the direction of new features/abilities of bitcoin have gone down one direction of one group of linked people.

3. mining pools issue new coins.. new coins are issued ~144 times a day. if new coins were not issued then all 21mill would be in existence and no more coins could be made

4. core can and have proposed to increase the units of measure.. as part of their lightning project the main devs are trying to push

in short
bitcoin does not have the same ethos of 2009-2014

firstly governments dont care about bitcoin. governments are comfortably sitting on their legislations that keep fiat in circulation.

in short.. as a real example
the UK does not care about the Euro currency becoming popular because the UK has legislation to keep the pound in circulation. so the euro could be used more popularly wherever it likes hand to hand, but the banks, taxes, fines and salaries of the UK will still be measured in pounds.

popularity will not cause a economic change.. legislative repeals need to be done.
bitcoin wont change things through a popularity contest. it has to be a political contest.

yep its not a 'economic threat' reason as the OP presumed. its about nefarious usage.

the more specific reason that these red flags are raised is that sometimes a business has been highlighted as receiving funds linked to a crime. or more commonly that scammers send funds to things like kraken, then the scammer cries wolf to say he has been defrauded to do a chargeback /bank wire reversal, thus making kraken look bad and become an alert to banks that see funds moving to kraken due (yes its the main reason) to chargeback scammers

this is stupid.
when someone buys bitcoin. the fiat does not burn and evaporate into a cloud of dust. the fiat just transfers from the buyer to the seller. banks know this and know that bitcoin is not a economic threat. (fiat still circulates, it doesn't disappear)
so anyone saying its a 'economic control' ploy is just making an uneducated opinion based on rumour and not fact.

the reason that banks are cautious about people receiving fiat which is linked to a sell of bitcoin is to do with the traceability of what that bitcoin was initially used for. banks are cautious to not handle funds of drug dealers and child molesters and other laundering(mixing) stuff

and while the tide of perception could have changed where bitcoin could have been used as a common currency to buy food, rent, vehicles. the whole tx fee has crippled the consumer/retail potential use of bitcoin for common use. and so banks still see bitcoin as something predominantly used for the more nefarious stuff.

now going back to the 'economics' opinion some have. banks and governments have legislation to keep fiat in circulation. things like the national minimum/living wage ensures people get paid in a certain currency for the majority of people. taxes, fines, public sector businesses/services receiving and using fiat from the treasury.

all of this means that bitcoin wont take over a countries economics just by existing. instead lots of legislation would need to be repealed first no matter how popular bitcoin became, and as that is not something that is happening at any time soon then its not something banks have to care about.

in short
its like banks in canada do not care about how popular the Euro is, they also dont worry that the Euro will b a economic threat to canadian banks just because of popularity. because there is canadian legislation that keeps canadian dollars in circulation where taxes, salaries, fines and public services are circulated using canadian dollars in canada, not the euro

attack on the network?
mining pools moving away from bitcoin is not an attack. at best its desertion..

hashrate is meaningless. nodes can reject blocks out of bias for many reasons. and many have
price is meaningless. it goes up, it goes down. its speculation. 10 tokens at $1 is the same as 1 token at $10. the net result is the same for fiat profiteers.

all that ultimately matters is what coin people use, accept and handle day-in day out.

EG
myspace had the biggest user adoption of any site. but then when people realised something else can handle their needs better. it didnt matter that myspace came first, it didnt matter that myspace was popular. all that matters was UTILITY

so just keep an eye on what coin things like coinbase, bitpay, gyft and xapo accept as the real world merchant acceptance coin. then you can tell which coin is best

until we see merchant acceptance shift.. all i see is speculation to cause price drama for fiat lovers to run off with more fiat

unless a coin actually is used as a real world currency (coinbase/bitpay merchant shopping cart acceptance) then all other things are just speculative points of interest for a bubble token of investment.. and not anything to do with a real world currency

even the 'who has the hashrate' is meaningless. after all even if a pool had 100% of the hashrate. core can just IP ban any node communicating with that pool and reject any block from that pool. and thus that pool ends up hashing for nothing. while a core based pools get accepted even at a 1% hashrate
the code rules are not about hashrate, but about what block is acceptable. so hashrate means less than the rejection criteria core coded in

anyway

yea the price might jump up and down
but a 100% rise of a coin for $1 is the same net effect as a 100% rise of a coin for $100,000
basically you buy $10 and get $20.. it doesnt matter if you obtained 10 tokens or 0.00001 to get that. the result is the same

so price drama is irrelevant. it goes up it goes down.. just like the sun. eventually people get bored of looking at the sun and accept what is expected to happen.

what really matters is how USEFUL a coin is for actual use.
such as fee's and merchant acceptance

so while bitcoin is losing merchant acceptance. and other coins are not really gaining merchant acceptance. i do not see any of 2017 drama about coins actually being positive.

yea many fiat lovers are happy they gain more fiat when they run off.. but thats not what real crypto is about. so i dont care about their excitement.

what people need to be looking hard at is the merchant adoption and the freedom(ease) of use of a coin, to then know which is better

sipa/gmax/lukeJR control bitcoin.
the bch / btc event was NOT consensus.
kittens did NOT have control.

the decision to avoid consensus (choice by kittens) was taken away from the kittens back in august
https://github.com/bitcoin/bitcoin/pull/11128

it was always going to be an alt due to the decisions by 3 people.
atleast research your opinion and learn the facts. bitcoin decision process for updates is not decentralised