They're habituated to it maybe. It may be "comfortable" because they know it well and that familiarity allows people who likely had unstable home situations to appreciate the comparatively stable situation of prison to be preferable.
I had a whole response here but I took it out. I'll put it this way - you don't know what you're talking about and my name is right there in my nick. Do some investigation then return and tell me I'm lying.
Most guys I know that have done time certainly don't love the cops. But when you get caught doing a crime they don't protest either.
And you call me tough guy. That's funny. I told you I committed crimes, that I was a violent person in the past. Then you attack me and you want me to be civil? I don't have that in me sorry. I'm a victim of the system you see. Pity me.
Some people enjoy prison. I imagine they're not common.