have you ever been to prison? it is a tough life in there. no matter what you did or whether you were wrongly accused for something, prison is not for everyone. it is obviously lonely as you gets separated away from your family. it can get boring, not being able to do what you want.
but gambling, even tho is prohibited, is often what entertains most prisoners. there is no actual money in prison so they often exchange in other forms of currencies like food or smuggled items. even their way of gambling is smuggled. cards, dice and even information from the outside are all smuggled.
the reason why gambling is prohibited tho is because it might escalate into fights if someone for example loses and doesn't pay their debts
just shows how gambling will always exist anywhere
I have not been in prison but I understand that those places are the worst place somebody can go because it takes years of your life away and give you no much hope to live for, however I no that gambling could be everywhere but it might not be that easy as it may have seen from the way you say it concerning those in the prison because one thing that almost all the prisoners have in common is fighting to become the strongest person in the place and when they have someone like that he mostly abuse his power to influence the rest including in the gambling because you could win him in gambling and he turn the table around.