Yes, actually, the American mafia has declined severely since its heyday. There are surely many reasons, as it's part of a broader decline in crime in recent decades, but the increased difficulty of cleaning dirty money is part of it.
And crime has definitely gone up because of cryptocurrency. I'm not sure how much it has affected the more traditional sorts of crime, as I don't think it's much of a help in turning dirty cash into clean assets thanks difficulty of exchange and the ledger acting as "prosecution futures". But ransomware has grown massively thanks to cryptocurrency. And ransomware gangs have grown correspondingly in size and sophistication thanks to having all that money to spend.
And crime has definitely gone up because of cryptocurrency. I'm not sure how much it has affected the more traditional sorts of crime, as I don't think it's much of a help in turning dirty cash into clean assets thanks difficulty of exchange and the ledger acting as "prosecution futures". But ransomware has grown massively thanks to cryptocurrency. And ransomware gangs have grown correspondingly in size and sophistication thanks to having all that money to spend.