Bitcoin is really popular when it comes to crimes. A lot of criminals use bitcoin for the same purpose. They doing miney launderung using bitcoin; buying illegal drugs and firearms in the darknet where you can find things that relatedly illegal. The illegality of bitcoin in some countries has reasons. The government banned bitcoin fod aone security purposes. They don't want their people to be involved in such crimes on the internet. In that way they can lessen crimes and make their country to be more safe and secured.