this was not a simple screw up though! they were all in the same circles on same websites with their real IP addresses (no Tor or anything) and were also signed up on centralized custodial wallets like Coinbase with again the same IP address and their wallets were also linked to the same address they used to scam!

what they did was more like going to rob a bank and then taking your drivers license out to show it to the camera with your face and the bag of money in your other hand

that is not at all true.
for starters every shitcoin that was created has been copying another concept and even coins that are less shitty have been copying bitcoin concept. and that is the case with every single altcoin out there. and there is no law against that because the "concept" is released under MIT license and there is no "company".

as for investors, they don't give a rat's ass about the project being good. all they have ever cared about was making profit, that is why we always see shitcoins with biggest pump and dumps are the most popular even if they were clear scams. evidence is the top 10 altcoins!

it is not really a juggling act though. it is just as simple as it has ever been even before SegWit but with a tiny change that they compute fees in terms of "virtual bytes" instead of "bytes". then it is a matter of comparing the rates just like before. if one transaction is paying X and another Y and X > Y then the transaction paying X is preferred.
looking at this from outside seems complicated because people think in terms of raw bytes.

the 2 of 3 multisig wallet seems like a good setup to me, just want to remind you to make physical (eg. paper) backups of the keys used by each of them and store them somewhere safe. you'll never know what disasters can happen in the future.

but i particularly dislike the multicoin wallets for bitcoin. they should never be used in my opinion, this type of wallets are usually closed source and/or very weak in sense of security. they are also not popular so they aren't really reviewed by any experts the way actual bitcoin wallets (eg. Electrum) are reviewed.

i am not sure if i want to read an article that has a title calling this rise a "massive surge"! anybody who has ever looked at bitcoin charts (you don't even have to have been around since the data is there for all to see) knows that bitcoin "massive surges" are at least above 80% like what we had in last month of 2017 when price went up about 120% in less than 2 weeks.
in comparison the rise we had recently was a tiny rise at first and within days it reached a size which i would call a medium rise.

i think all the reasons mentioned are already correct but they all contributed a little to the rise. keep in mind that before the Covid panic (which had nothing to do with bitcoin by the way but still affected it all the same) price was already rising and testing $13k so we are still below that mark!
but i think gold rally might have have a bigger effect on the confidence coming back to the market and investors jump at buying bitcoin.
and of course with the way US has been printing Dollar like crazy, the value of dollar is bound to dump hard even if slowly. and that dump means bitcoin price goes up.

in reality $20k is just an arbitrary number that doesn't matter one bit. but when it comes to users behavior they are all known to build up imaginary resistances at previous all time highs, which is  why sometimes they are referred to as psychological barriers.
we saw this last time too when price got close to $1200 which was the ATH of that time (during 2017 bull run). people tend to sell more for some reason and regret it in about a month.

what would i do? mostly nothing because i don't day trade bitcoin and i have already bought what i could afford when bitcoin was undervalued. by the time we reach ATH we will be in a full bull run mode. if i had some extra money to dump to buy bitcoin then i would do it then like i always do.

you can't delete an address from a standard wallet which was created using your seed. the imported addresses in an imported wallet are delectable as it is the nature of the wallet. all you have to do is to right click that address and select "Remove from wallet" option.

the problem i have is with when you check an address on a block explorer and it shows the entire inputs and outputs for each transaction's. and when the address has send/received a lot of this type of transactions with lots of input/outputs it becomes tedious to go through the history of that address. and that is unfortunately what most block explorers do these days.
instead it should be simplified, the inputs should be hidden except for the first 2 or 3 with a button saying there is more and the outputs should only show those that involve the address you check not all.

even though there are thousands of miners around the world, they are going into "groups" to share the work so each "group" ends up working on the same block and then share the reward. these "groups" are the mining pools and there are about 20 of them. so the competition is actually between these pools and the reward goes to the pool which then it spreads among the individual miners depending on how much work they contributed to.

i know you love bear market but bitcoin has so far been strongly bullish and ever since yesterday that we saw the rise to $12k followed by the correction the market is even more bullish because of that correction. it is still too soon for reaching ATH though, the $12k situation should be a clear indication of that. it still is because of all the sell orders that are placed or are waiting to be placed all the way to the ATH by traders.

that makes sense.
i believe wallets that are designed like Electrum that have focused on both BIP-32 (HD wallets) and cold storage mode (offline-online) must use non-hardened addresses because if they don't the online-offline mode won't work since it requires master public key only on the online wallet.
core doesn't have this feature so it gets away with it.

when re-installing windows there is an option that keeps a backup of your documents and other data and only upgrades the operating system itself. you might have chosen that (i think it may be on by default when you already have windows installed). look around in your C drive and see if you can find that folder. if you did then your wallet file should be among those files.
other than that i don't think even recovery tools work in your case because you basically format the entire drive and then rewrite most of the bytes.

we start by discouraging people from using any tool that is severely flawed. for example i have been telling people to avoid using the site i mentioned above for over a year now. good news is that many listened after they saw the flaw. that goes for any other wallets (desktop, mobile, web,...) that are doing a poor job.
next step is reaching out to developers and asking them for improvement, this could be done by creating issues on their github repository or better if we have any programming skills then we should start contributing by writing code and creating a PR instead. and obviously anything that is not open source should not even be used by anyone to begin with.

both of your suggested wallets are terrible in general and specifically for someone who is looking for a bitcoin cold storage.

for starters they are both mobile wallets and this category of wallets are always far less secure than a desktop wallet.
secondly they both are token wallets first and then have some bitcoin wallet options. which means they are only good if you want to store garbage in them not bitcoin.
and finally which is the most important factor, both of these wallets are closed source so you literary have zero security when using them. (TrustWallet has some source available but not all)

well they don't want to learn and they keep using the same low quality services and even recommend it to other people. the problem is that their choice affects everyone else's experience too.

it is not that easy but it is not as hard as you may think either. for starters a lot of clients lack the option to let user set any fee they want specially in fractions of a satoshi (like setting 5.25) so they have to jump up. they also don't give users a concise information about the memory pool status at the time they want to create a transaction so that user can make a better decision.

i don't see how much they helped at all because according to the story i've read they caught them by investigating centralized databases which had nothing to do with bitcoin in first place. it was mainly the forum they all hung out and communicated in called "OGUsers", there was also Discord they used and among their accounts in this site they were also used the same Email address and same wallet to connect to Coinbase website and Binance. not to mention that their IP addresses were all the same (no TOR, no VPN,...) and were used in all these places!

this makes me wonder why the hell are the media using the term "mastermind" for these dudes

https://www.wired.com/story/how-alleged-twitter-hackers-got-caught-bitcoin/

and wrong analysis is the worst of all!
you don't "calculate" the price. the price is what it is and the demand wants it to be. and it has nothing to do with how many "early addresses" have bitcoin or are lost.
in bitcoin market it is very easy to get caught up in meaningless factors and keep trying to come up with an analysis that seems to be making sense but it is just an illusion.

is there any implementation that uses hardened keys?
all the paths i have seen with hardened paths use hardened indexes all the way to the child then the child key itself is regular. like BIP-44 where the path for each key is m/44'/0'/0'/0/0 m/44'/0'/0'/0/1,...

well 9500 satoshi is just too low (it is barely worth 1 buck) so this transaction can be deceiving. a larger amount (not that i'd recommend it) needs to be sent to create the incentive for a double spend and see what happens.
additionally the "bots" may not be watching SegWit witnesses since they are usually old and written pre-SegWit.

so many mistakes all in one place

1) a little nitpick but it is market cap. or market capitalization
2) it does NOT represent value. it is more like a size of the market (that is the case for cryptocurrencies at least) and it is only accurate if the supply is real which means no premine, no ICO, no secretly owned coins by the dev,... it is also defined for stocks and not much else. so it doesn't make that much sense to even be used for something like bitcoin or any other cryptocurrency for that matter.
3) it has nothing to do with volume and exchanges or sites like CMC can only fake volume. market cap is the result of price multiplied by supply. the price is obvious and the circulating supply can be calculated by anyone. neither can be faked. so the result is always an accurate number, how much weight you want to put in that meaningless number is your own choice!