Bitcoin is being used for illegal activities as much as fiat is being used for illegal activities, it doesn't mean it's the fault of bitcoin or that bitcoin is a bad currency.
There's criminals everywhere and bitcoin is attractive cause it's very anonymous to all those criminals.
criminal activities are even higher with fiat. and this is btw a sign of a good currency. everyone can use it. if you leave certain people out and you can decide who can use it, then you have a bad currency.
Yup, fiat world is too big, more crimes, maybe criminals will use bitocin to do bad things, it is beneficial to bitcoin price.