Hello,
From what I read, someone who sells btc sometimes has trouble receiving the fiats in its bank account. If the sum is large, the bank turns on all its red lights. I guess it's not a problem for someone famous, but for an ordinary citizen, how it happens if he lives modestly, recovers his private keys that he lost 10 years ago and finds himself with millions?
It's not a problem at all. There are many wallets nowadays that you can use to cash-out your money. And for me, why do you need to transfer all millions of dollars in a single event if you can divide your money into different assets such as pouring them in different exchanges or foreign stocks, buy different cryptos and save in different wallets. Just make sure you'll not forget the seed phrase.