Well, its their problem and not ours. As a saying goes no bad deeds will be left unnoticed. So when you make an evil deed of course the btc you acquired will still be traceable. So as to play safe, just earn bitcoin legitimately so that the eyes of the public and authority will not search for you.
Also converting a huge amount of btc into fiat is a bad idea since the concept of bitcoin is decentralization and going away with the banks. This means that you make your bitcoin wallet as your own bank. Then just withdraw small amounts when needed there is no need to convert everything into fiat currency.
You don't get it, anonymous wallets become traceable 100% as soon as you send 1 cent to an exchange.
So let's say you operated a casino in early days or porn site or bought cheap coin off dark web.
Bingo
U now not anonymous as u do anything on an exchange, so if u bought into btc as to being anonymous it's not.
Now let's say u own a business u put off the radar cash into it, thinking it can't be tracked.
So the BS about anonymous wallets works until u try to legitimize the coin.
Then if u did numbers with BTC and now have millions in value, it's trapped in BTC, u can't get more than ,50k usually out of an exchange in a week.
Now to some that sounds like a lot, well to early players on the net if u made say 5k weekly investments into cheap coin u will never be able to get the mega millions u now own out without full audits.
So lots of players are trapped now in heavy value wallets
The only way to not raise a ton of flags is private deals off the exchange grid.
Anyway, if u exit the game u get exposed.