You'd be surprised to learn just how many wise guys, from soldiers, up to the bosses themselves, ended up broke because they were either;

A) Degenerate gamblers all their lives, who blew every dollar they ever made.
B) Hoodlums who never learned "how" to earn in the streets from day one in the first place.
C) Were one-trick ponies with one way to earn, once that hustle ended they collapsed financially.
D) Were guys who were strictly "street guys," well-versed in the rackets, but with no legit business savvy. And they got "long in the tooth" so to speak, didn't have anything solid to fall back on.
E) Were guys who never wanted to invest in legitimate business. And, once again, as their racket revenue dried up, they found themselves dead in the water.

**And a hundred other reasons...that all ended up at a dead end for them.