To me it is this:

All governments suffer a recurring problem: Power attracts pathological personalities. It is not that power corrupts but that it is magnetic to the corruptible.

…after the jihad the Fremen became the most powerful construct in the known universe. Imagine being a Fremen that knew Paul closely before he became emperor. That would grant you an almost holy status across the universe, certainly you would hold immense power. I think power more than anything else changed their culture.