What a stupid question.It is like asking the director of a bank why he is closing his bank every evening.Maybe they wanted to know why he didn't use his talents legally... But how could an expert of bank robbery work legally? Did the police ever say to him "You could give us good advice, or you could to some security company!"? Did they? Or didn't they?Today they try to recicle the hackers and crackers as security advisers.
Its hard work to steal money, lots of money, out of a bank. In former times most experts preferred to execute the take away when the money is on travel from one bank account to the other. This method is is still popular but not as spectacular as a beautiful wild west movie of a robbery of a steam railroad train.