The problem here is that the system should have some way to fight these criminals because we don't want bitcoin to be associated with drugs and sex trafficking, but the problem is, by solving these problems we should get rid of anonymity which is a pillar for the bitcoin technology, so it can't be done. And this problem might be a big obstacle in mass bitcoin adoption and regulations that are coming.
Almost every single currency or asset that exists in the world is used somewhere in a criminal or bad activity, and that doesn't really make much of a difference as those using it are the ones who are bad and not the currency or asset that is being used. People used to think Bitcoin is a currency used only in criminal activities some years ago, but did that stop Bitcoin from becoming famous or proving everyone wrong? No.
So no matter how hard a certain group of people or authorities try to convey it so that it looks bad and people stay away from it, it will become more and more popular and people will start using it more. So we don't really need to worry about that thing.
True. I can't believe some people and even politicians are accusing Bitcoin and other coins of that. But fiat was involved in crimes for centuries, but you're not banning it because of that!