In my limited experience it actually takes a bit of time, luck and hard work to do well in crime which is why it is mostly an activity of the desperately poor and the not very smart in many societies. But it makes for better TV/Movies to focus on the outlier drug kingpins and Mafia dons than the guy selling pot 24/7 to pay his rent or stealing bikes and purses to get 20 bucks for rock.
But anyway, in our game the criminal thief may have started out meager but with a bit of card sharking, pocket picking, dealing with shady NPCs and creative loot distribution he has definitely not stayed that way.