of course bitcoin is used for illegal stuff, we cannot do anything about so i dont worry about it
and that is really not a bit problem because illegal activities might be done in all kind of currencies and not only in bitcoin. if we think about the Dolllar i think still dollar will be use for most of the illegal activities, therefore i there is no worries about this and that part of every society and not only bitcoin is responsible for that.
All of your statement is always possible to have happened in every time, And the problem of here is bitcoin getting blamed by some people is think the bitcoin as a triggers an illegal activity and they're very very wrong at this, you're right another currency giving a chance using for illegal activity.
but sometimes the criminal it no needs a currency for doing their criminal activity but just exchange their personal service into illegal goods it's can be. a many people having little thinks always know to blaming a one party and not seeing about the role and chance of another party.