According to studies, bitcoin for illegal purposes is used from one to ten percent of cases. This is a very small percentage. All advanced technologies, and even just sharp objects are used by criminals. Maybe we will not allow people to have kitchen knives, they are very often used by criminals for murders?
 This problem with the use of bitcoin for criminal purposes is absolutely conceived. It is very beneficial for states and banks to further use this topic and restrict it in circulation, or even ban the decentralized crypto currency and, above all, bitcoin.