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
It is a bit different when compared to prisons in my country, here it is common knowledge that prisoners can gamble in prison, whether it is like gambling or betting with other prisoners or online, but it is important to know that prisoners here can only do it according to their ability to pay for the freedom in these activities, so it will be different if a prisoner is in a state of inability or poverty which does not get certain freedoms, and has limitations like the prisoner you mentioned. Personally, I have never been a prisoner, but stories like the ones I told are already common knowledge and are circulating everywhere, including being told several times by former prisoners who have been involved in gambling activities, and various other things.