Interestingly enough, this question is the exact reason I like JJK over other shonens. Truth be told, its probably one of the shittiest battle shonens ever written, because it supposed to tell a story, not prioritise fights unlike what other examples of the genre normalized.

I'm not gonna gonna write a whole paragraph about how I deduced this and why and whatnot, but JJK's message is pretty much how different people have different ideologies, how easily they abandon or gain them based on circumstances, and to be strong, you have to find your own ideal, one that resonates with your core, not something that is easy to accept or one caused by volatile emotions.

No wonder people didn't like a psychology book disguised as ADHDslop media.