I recently read the diaries of a prisoner who admitted that it is very easy to get into trouble there because of your gambling. The order is as follows: first, a person comes to a cell and others look at what he is in jail for, how dangerous he is, how adequate he is, and so on.
And after that, there is always a hardened card lover who tries to somehow make friends with this guy and try to win everything he has, so gambling in prison is a very dangerous place, because people who have nothing risk losing themselves there.