Understanding why people are assholes is worth it because we learn how to deal with them,

I guess the question here would be - if the stroke made him more of an asshole, then - as you seem to be implying - what’s the cure? Or if you acknowledge that there’s not really a cure, how does knowing that a stroke caused this help inform our ability to deal with this?

and maybe even prevent less people from becoming assholes later.

How would that work in this case? Preventing strokes definitely seems like a good idea, but that’d be something already being pursued to the fullest even without the additional personality change angle.

Or are you suggesting that there’s a way to help a stroke victim prevent their personality change, lessen it, reverse it?