That... is quite hard to explain.
Pride just comes naturally when you have something of great quality. Whether it's strength, knowledge, skill, talent, beauty... anything.
Maybe it's a sense of identity and worth. Like, if you're not as strong as how you usually are, or if there's someone stronger than you... it feels like you are robbed out of your identity and you are no longer worthy of anything. Strength is all you have, and being number two is the biggest loser.
Also, Pride's best friend with Fear, I guess.
When you already stand on the highest ground... there's no more way up. The only place to go is down; and to fall down off this height will hurt you terribly, if not kill you. So during those pinching times, on the pointy, dangerous peak, your only companion were pride and fear.
Imagine someone shows up to take that peak. Where to go, then? Fall down the rocky cliff and die? Of course not, therefore you stand your ground and fight, and fight, and fight again.
Anyway......... pride is a hungry fella. Complicated, and wild, and merciless, and stubborn, and ... it's a lot of unpleasant thing, really. But it's also addictive. Damn addictive.
You got to experience it yourself to understand.
why do strong people have the biggest pride?? why tf they have to constantly fighting in order to be known as a strong? ofc im talking abt that andre not our MC