I believe most of them 'convert' to get better food, as simple as that. There's also safety in numbers and they take on the role of a prisoners 'union'.
Most of them, having availed themselves of the benefits in prison, will, thankfully, revert to their pilfering, drug dealing ways on release.
However, there'll be a few 'right thickos' who, while they've never thought about politics or their role in society, have a sense of grievance, a sense that life's not fair, lol.
For instance, why do the police pull them over in their cars just because they haven't got insurance, or say, a driving licence when they 'obviously' wouldn't pull a white guy over for little things like that.
When they get hold of that seething resentment, they can feed it and then mould it to do 'bad things'. That's my theory, anyway, and I'm sticking to it.