@KINGwaldo
Well, the apocalypse would change a man. Then, add on a sudden rise to power. Most common men wouldnt be able to handle such a sudden shift, falling to its corrupting allure more easily.
And, honestly, the scum and filth are just more likely to survive. Not because of some cosmic joke, but because that's their personality. They're more inclined to abandon and think about only themselves. Plus it gives nice little stepping stones for the protagonist to step upon on their rise to the top.
@KINGwaldo
Ah, I understand now. Honestly, the most bare-bones answer is that most of these martial arts stories are done simple and without much thought. So you come across a lot of tropes and stereotypes in them.