there actually is not much of a relationship between the two.
sometimes BTC rises and ETH follows. sometimes it falls instead.
sometimes BTC falls and ETH follows. sometimes it rises instead.

but generally speaking, whenever bitcoin is rising (or falling) other altcoins fall. the reason is not completely clear. i have some theories though.

i say it is partly because most people expect the altcoin falls during times like that so they act faster to prevent losses. that always creates panic sell follow ups. as this happens more often, more people catch on the pattern and start selling and soon an altcoin dump becomes a common thing during bitcoin both rise and falls.

the other part is due to arbitrage opportunities that bitcoin rise creates specially in the altcoins with fiat market like ETH.
for example lets say bitcoin is $10,000 and ETH is 0.05BTC or $500
bitcoin goes to $14,000 so if ETH stays at 0.05BTC it means it would be worth $700 but it can't just rise like that! nobody is going to pay $200 more for it. additionally there is arbitrage opportunity which creates some sells on both markets and "act of selling" is always causing panic sells, stop loss orders kicking in, bots starting issuing warnings, the alerts going off,.... and causes the drop to happen. so the final result would be ETH at $480 and 0.034BTC
(numbers are just for example).

on top of it all, there is always bubbles to consider. specially in a coin like ETH which will burst due to this sell off.

you forgot to mention what coin?

as for deposits i know there are some shitcoins with broken blockchain, no/very little hashrate which are susceptible to 51% attacks and these attacks to happen sometimes on these coins. that means losing a lot of money for the exchange if they accept low number of confirmations so they increase it for such coins.
it is normal for big coins like bitcoin(2), litecoin(6), dogecoin(6), GBYTE(1) ... unless of course there is some issues with any chain like the August fork of bitcoin.

as for withdrawals, the withdrawal fees they use for most coins that i have checked is not higher then the fees other exchanges use. maybe some of them a little higher but not by a lot which means calling it "outrageous" is a little unfair. for example it is 0.002BTC for bitcoin which is the same as bittrex IIRC and c-cex and couple of others. it could have been smaller and should be a little smaller.

some random dude said it on the internet, it MUST be true then

and why do you think it is a weird thing? or call it rumor? 30% drop is actually a common thing to expect after each big rise like this.
go here: https://bitcoinwisdom.com/markets/bitstamp/btcusd set the interval to something like 1 Day and you can zoom in and pan left. check the price from $200 (2015-6) to $14000 (2017-12) you can see all the drops so far.
after each big rally (eg. $317 rally in 2015-6) there is big drop (-37% in this case down to $198).
more recent example: from $1350 to 891 (-34% drop) back in 2017-3

now we are on the rise. soon this round of rise will end and there will be some drama and FUD and price will fall down. about 10% correction. then it is possible to become bigger and go down as big as 30%.

those who want to trade altcoins are already trading. they don't just leave altcoins because bitcoin is rising.
how much did bitcoin rise in past 24 hours? 10%? 20%? that is pathetic compared to the rise of altcoins. for example checking the coinmarketcap.com you can see Decentraland (MANA) has gone up nearly 200% in 24 hours. TRON (TRX) has gone up nearly 130% in 24 hours and lots more every day.

the trading funds of real traders will always remain in the altcoin market and just goes from one altcoin to another. only the bag holders and newbies who buy on top and lose money sell when bitcoin is rising and go back when altcoins have already pumped and are in bubbles.

bitcoin adoption and price, that is up

currently there are at least 4 altcoins scheduled to be created in December (this month). and as we go on, there will be a lot more. possibly even 50 in the following couple of months. but soon enough they will all die and disappear and this form of forking bitcoin will be forgotten specially since starting from a 150 GB blockchain is very hard!

forks like these (bitcoin Diamond, silver, ...) are bullshit, they won't have any effect on bitcoin. nobody even cares about them. the coins were distributed 1:100 for each bitcoin and that shit is worth about 30000 satoshi after a massive pump. these things can not even put a dent in bitcoin price.

you say that as if you don't believe it!
the thing is, majority of the altcoins specifically the top ones that everyone hypes these days, are worse than bitcoin. you just don't see the issues in them because they are not used. they just hype it and pretend they are better, more promising, better scaling, etc. but when it comes to reality they all fail, harder than bitcoin. google crypto kitties and see how it crippled ethereum for 3 days now.

and yeah, bitcoin will crash like it always does after a big rise. but in the end it will pick up again and continues rising because it has that "real adoption as a currency" not just speculators who are in it for short term.

it is just a start. that is how ethereum should work, the Crypto Kitties is not doing anything wrong or out of the ordinary, it is actually using ethereum as everyone else i supposed to use it. the problem is that ethereum is not capable of handling this much usage despite all the things that you hear in the advertisements.

and i say it is just a start because people seem to have liked it and i saw yesterday that someone released some simple tutorial on how to make your own thing similar to this project. and soon there will be more of these and things will become even harder.

you are seeing these problems because Ethereum has a lot of issues and bugs and it can simply go down like this. it has happened before multiple times. each time it was as long as a week before going back to normal but it will get worse as it grows. which is partly due to its scaling issue.

some people think just because some altcoin has faster blocks and seemingly fast transactions, it is a good thing but they miss all the long term downsides such as what you are experiencing here.

it won't fall now because the issues are not yet serious and also because the whale manipulators still want their profit out of this coin and they won't let it burn that easily. but it is a doomed project that will fail miserably in the end. and there is no stopping that.

this link from coinmarketcap.com doesn't show any fiat market. it is only showing a couple of altcoins which are being traded with bitcoin and the prices look normal to me. i didn't  check every single one but the tip ones like ETH and LTC seem normal.

checking the website of it also shows the same thing. they also have some fiat market which coinmarketcap doesn't list. i couldn't figure out what currency it is because it was called "QQC" and i can not find what it stands for. and the price was 81,000 QQC which doesn't match anything like CNY, JPY or RUR.

its like asking what is the sky blue!

there is no centralized authority in bitcoin because it is designed that way and it is supposed to be that way. meaning a decentralized or "a peer to peer digital cash" as the bitcoin original paper calls it. and people are interested in bitcoin, investing in it, and the price is rising because of this!

in other words being decentralized is one of the main aspects of bitcoin which gives it the power it has, otherwise we already have centralized currencies which we call fiat. if you want them then continue using the old systems that you know and use fiat.

it only has the benefit of being over-hyped because it has Ethereum foundation behind it with lots of money at their disposal to throw at pumping it and advertising it even with bribes all over the internet. otherwise nothing about ethereum is better by any means.

these other similar tokens which are smaller (in this case $7 versus $400) will rise up a lot more than the big ETH which is more of a bubble. those like waves still have a lot of room to enter a bubble phase which means their rise is much easier.

both of them have issues which means neither are good exchanges but we have no other choice but to accept it.
Poloniex:
a little slow interface and not so good charts
a good API
terrible support. you won't get any response for days.
it goes down if there is a big pump going on and you can lose money because of it.

bittrex:
better interface but still slow and better charts
a good API
terrible support but not as bad as poloniex.
it requires verification and you will have to submit your personal documents with them with your selfie. otherwise they won't allow you to withdraw.
it also goes down during big pumps but not as bad as poloniex.
worst thing is there are multiple scam accusations against bittrex. they have stolen a lot of money in the past couple of months and they are not even answering for it: https://bitcointalk.org/index.php?topic=1954598.0

maybe but not because of the reasons that you said here.

if you mean something like shorting bitcoin, they can already do that. and they have been doing it for a very long time. why do you think all this FUD has been spread with so much enthusiasm all these years? they were trying to make more money by shorting.

people always say this by the end of the year and the only thing that happens is a slow down not a drop nor a bear market.

what do you call a "significant pullback"?
a 10% drop? it happens almost every two weeks!
a 20% drop? that also happens every step of the way.
a 30-40%  drop? that also happened multiple time all along the way from $200 up to $11,000. in fact every single rally has so far ended with a drop like that!
90% drop? why should that kind of drop happen? and why do you expect that kind of drop!

i don't know how good these futures markets are going to be for bitcoin really. i think it may go south even for a while when they start up their markets. these types of market are good for bitcoin's publicity for a while when they are introduced and people see bitcoin is a real and viable option for investing, not what the media has always been spreading FUD about it.
in any case i am going to enjoy any kind of short term rise that news like this is going to lead to. it may even lead to bitcoin ETF being finally accepted by SEC too and another rally happens.

Ripple was pumped this year to a ridiculous amount. last time i calculated the pump, it was about 7000% rise! it is not yet dumped down to the real price that it deserves (something below 1000 satoshi) and still resides in a big bubble a little more than twice of what it should really be.

when it reaches that bottom, it will be accumulated and in a couple of months it will have another big pump like it had this year and another one in December 2014 and another in September 2013. (2015 pump was tiny). but it certainly won't take until 2020 to get pumped again. we will surely see a pump in 2018 but XRP needs to get dumped and exit its bubble first.

there are two ways that shops do this, and there is no right or wrong in my opinion.

- you can do what most of them do and accept bitcoin and forget about its volatility. it is a small risk compare to the potential that bitcoin has, and that potential means a lot more profit than you normally make.
and your shop is not going to get that much bitcoin income anyways so it won't affect your business. for example i have heard about a food truck that started accepting bitcoin in addition to cash. it increased his sales by a considerable amount but it still wasn't his main source of income, people still mostly paid him in cash.

- you use a third party payment processor service such as bitpay to ask for bitcoin but receive fiat. they convert it to fiat for you immediately and give you the value that you want. you may have to pay additional fees because you are using their service but if you increase your sales then that is justifiable. also you will miss out on the potential of bitcoin and its rise.

you should probably bookmark this topic that you have made here too. because in a couple more years you will be thinking the exact same thing and if your depression drugs don't mess with your memory you can remember that bitcoin was $10,000 some day and you still didn't buy when you could and you will have to buy more stronger depression pills for your mistake that you made today

market cap is meaningless. and you only get confused if you start comparing coins based on their market cap. for example Sia that you mentioned here only has a bigger market cap because it has a huge supply compared to INXT. ~630K versus ~31.2 mil

in case someone reading this doesn't know what market cap is:
Market Capitalization = Coin supply * Price
having a bigger supply gives you a huge M.C.

the only reason INXT can be a good investment, in my opinion, is that it is not yet pumped! it has been around for about 3 weeks and the price has not changed much. which means it has the potential to get pumped big time.
but at the same time, it is not listed on major exchanges (like poloniex) and its volume is low.

not the biggest "bank" but the biggest "bitcoin bank", which they already are. by definition you are giving up control over your money when you open an account with Coinbase and keep your bitcoins there and you get an account and some virtual numbers in return which Coinbase promises to guarantee their value.
the only difference is that they don't give profit on the money you give them (like your bank account does) and also they don't offer things like loans (which banks do). in any other sense they ARE a bank.
and being first and big, gives them that edge too. if they wanted they could become a huge company worth billions of dollars. of course being in US has its restrictions too...

considering the fact that CME bitcoin market is going to be active by then and also NASDAQ will have a similar market by the first half of 2018, and possibility of lots of good news like this coming out, i say it is possible to see that kind of rise. it is a small rise less than 50% if we finish this year with above $10,000 price. and with the way bitcoin is being advertised in the media day and night i can see a lot of money keeps coming in.


somewhat true but you can not expect something that has never happened before. reaching $15,000 tomorrow or today means rising more than 60% in less than 48 hours. that has never happened with bitcoin and not going to happen as this market becomes bigger.