Bitcoin is fully Anonymous so chance to use criminality. Bit coin is used to buy drugs and weapons.Bit coin exchange is used for most cyber crime activities.
Not all people used their bitcoin in cybercrime activities, here in my country bitcoin now is so popular and many people used it every day in their life and i never heard any bad news about bitcoin that used in criminal activities like buying drugs and guns. But since bitcoin transaction is anonymous and easy to use it is a big percentage to use it in criminal activities.