It was already used in crimes even when bitcoin was new criminals were also using it. They can hide their money in bitcoin very easily and it would be impossible to trace them.
Thats why you have a lot of scammers and if they have scammed you they will just send it to their wallet. Like it was nothing.
The fact, bandits still can rob your money without any technology like blockchain and cryptocurrency. You forget if you give them chance to rob your money, they can do that as nothing happened. Unless, the transaction of UG, cryptocurrency really the best option for those people, because their transaction mostly through online payment.
You are right they commit a crime because there is a chance I admit they are smart but unfortunately their intelligence is used for crime, They can do whatever they want to get it. to avoid evil we have to be careful and not give them a chance