Being a career criminal must be incredibly stressful and mentally/emotionally taxing. Especially if involved in organized crime (mafia or drug cartels) they might regularly get exposed to liquidations, work friends dying, extortion/death threats, and nearly escaping death. But because of the criminal nature of their job, there's no one they can talk to safely without getting reported to the police, except their lawyers.

Inspired by Breaking Bad and Better Call Saul, where exploiting attorney-client privilege is a central topic, why not start a law firm that operates as a therapy practice? Lots of criminals would be willing to spend serious cash to be able to process their traumas and work stress without fear of legal repercussions, with a few smaller criminals here and there who need help managing their stress during buglaries or properly handling conflicts with their accomplices.