In bitcoin's pyramid scheme, criminals have exploited the greed of people's ignorance and dreams of the currency. The essence of pyramid selling is a ponzi scheme, where a bitcoin is not fundamentally different from a tulip or a box of cosmetics.
In the event of an hacker blackmail, criminals use the anonymity of the currency, trying to escape legal sanction, COINS and cash here, there is no essential difference between just more convenient, lower cost.
In money laundering, drug trafficking, and terrorist crimes, criminals use the anonymity and high mobility of bitcoin to hide the flow of funds, which is the same as the effect of using cash.
Everything is a criminal tool if used by the wrong people and for the wrong reasons , there is no such system that is flawless there will walkways be people trying to go around it and exploit it, and bitcoin is no different, it is true that it provides anonymity which is good way for criminals to do all their illegal activities without being traced, but it also helps people who are not using it for illegal stuff to keep their identity and personal information from being stone, the point is for every con there is a pro and in my opinion it all depends on the person using it.