Because of the semi-anonymous nature of Bitcoin, its used in ransomware attacks. Hackers breach networks and hold them hostage until payment is made to them. Hospitals and schools have been victims of these types of attacks. However, unlike cash, which was favored by thieves in the past, Bitcoin always leaves a trail in the blockchain that investigators can follow.
Bitcoin or not, extortionist will always find ways to do their bad deeds. Though it might be true that bitcoin's pseudonymity can prove favorable to such organized crime, the regulations being enforced nowadays might change all of that very soon.