You could outlaw or regulate the mining and use of the coin in a country. It wouldn't be easy to enforce, but you could certainly but the law on the record.
You could increase taxes on cryptocurrency capital gains. Big exchanges would absolutely report those gains to the IRS and you could be on the hook for a bigger bill.
It's not impossible to regulate this stuff. Yes, some folks will figure out ways around the regulations, but you'd catch most tech-unsavvy people just fine.
Laws don't target organized crime. Well organized crime influences the law so it would target regular people and politicians could say they are tough on crime.
You could increase taxes on cryptocurrency capital gains. Big exchanges would absolutely report those gains to the IRS and you could be on the hook for a bigger bill.
It's not impossible to regulate this stuff. Yes, some folks will figure out ways around the regulations, but you'd catch most tech-unsavvy people just fine.