> corrupt criminals and mafia types who have a need to covertly hide cash

You're describing the people that use actual cash to launder and hide, well, cash, and that have done so for centuries, long before crypto had even been invented.

A few web searches on <big bank name> + "money laundering scandal" (e.g. "HSBC money laundering scandal") can offer valuable insights.

>> that have done so for centuries

There is no doubt crypto processes trillions of dollars of illegal cash. Way easier for the illegal cash industry to wash their cash than ever before.