I'm curious about this.  For the people who are long term holders of btc and they either never sold any btc to coinbase to convert to fiat and just holding it until btc hits their price target, do people like that not cash out big amounts at once when they are ready to sell?  Imagine someone who is a long term holder of btc and they either never sold any btc to fiat or sold only a tiny amount and then transferred it to their US bank account.



But then btc hits a huge price and now they want to sell a good portion of it.  Well if you are a coinbase customer for a while but you never cashed out any btc or only traded small amounts, isn't there going to be an issue if someone was to send some btc from their hardware wallet or trustwallet or electrum to it and then trade it for usd and then cashout?  Like imagine someone goes to transfer 1 btc to their coinbase account when their biggest btc transfer could been only $2000 worth from back then.  Then they convert it all to usd.  Then they do an ACH bank transfer to their US bank account or a bank wire transfer.  Isn't coinbase or whatever exchange they are using might ask them questions like how did you acquire this much of BTC for someone who never transferred this much btc to their wallet before?  And even if they did, they never ever sold it to usd so that would be deemed strange to them? 



Or imagine someone who have 1 million dollars worth of btc now in their wallet and they want to send it to coinbase to cash out.  But their biggest transfer to coinbase could been $2000 worth at the most or even $50 even.  And say the biggest amount they ever sold or converted btc to or from could be something like $25 only.  Wouldn't that person who wants to convert their btc to cash and then to their US bank account have to be careful to not send too much btc at once or trade too much at once or send an ACH or wire transfer back to their US bank account at once because coinbase or the exchange they could have an account in for years but never or rarely use it could flag them?  This is all assuming this person's btc is legitimate.  Would coinbase ask prove of your crypto in situations like this if they suspect something fishy?  However, couldn't they just check the blockchain and then there would be no issue?  The one issue here seem to be if you have lot of btc from back then or even now and want to cash out and never sent this amount of btc to coinbase before or sold this amount before, then you should do small amounts first and then go higher?  The thing is if these were the same amount or similar amount of btc you bought from coinbase many years ago and you had sent this to a hardware wallet or trustwallet or electrum, well obviously it wouldn't be fishy to them.  But if these coins are from where you acquired it from somewhere else and now sending it to coinbase to cashout and it's legitimate coins, does one need to be careful not to send to much or sell too much at once?