of course bitcoin is used for illegal stuff, we cannot do anything about so i dont worry about it
I think we will not know the purpose of transactions of everyone in bitcoin. although the transaction id they can see but we will not know what they do with the transaction. so I think bitcoin is great to be used as payment for illegal goods. and I do not know if many people are using bitcoin to buy drugs and so on
It seems to be that some people use bitcoin for illegal thing like drugs but the same thing happens with other currencies and even with gold too. And to be honest, dollars is on top for most being used illegally its not a big deal, and I think the government should focus on those illegal activities not on what currencies being used for them.