somebody is more then willing to pay tax. But should you not show HOW you made that amount of btc (the same with 10 million in cash, if they stop you on the road with ten million in cash they will put you in prison if you can not say where it came from)? authorities could think that somebody is a ransomware attacker or a darkweb criminal. The lawyer somebody spoke to said that you have to be able to show the source of your funds. He said something that criminal law says that you have to have proof for an offense. And that in tax law they can fine you on assumption. Somebody is confused and afraid.
selling it part by part, that is not a good option because it will take a life time. and somebody does not believe that btc will be the one and only for the rest of our lives. As well, if you exchange bit by bit, and it is a million in a few year, and somebody has a 1500 euro salary, that might be a red flag for the bank. somebody has already loads of cash and prepaid credit cards. exchanging bit by bit does not allow you to invest either, you are not able to buy a house with it, not able to invest a million in a companies etc..
the question is: will authorities allow it, if somebody has millions suddenly out of nothing and can not show where it came from. somebodys lawyer says he does not know what will happen and that he has to write the authorities which he is doing now.