I think history has proven that there will always be a underling ready to take his chance at the top. We need to look no further than at something like the drug war in Mexico or even to the US to a smaller extent. A young, brutal cartel member rises to the top with his crew and lasts as leader for a few months or years until he is murdered by the next young, smart, hungry up and comer. It is a never ending cycle, even in Mexico where people are getting murdered everyday someone always thinks they can make it big and stay there.

But I imagine it has a lot to do with it being only alternative for these people. Just imagine you are born in an extremely poor area with no hopes of accomplishing anything. Better to take you chances as a rebel leader/cartel member because as short lived as it is, it's better than living and dying hungry in your small rural village.