The whole "evil" side of alignment is stupid. "Selfish" would be a better choice.
Eh, not in D&D/pathfinder/etc. universes, usually. Evil is, like, an actual
thing there, with its own pantheon of concept enforcers, physical manifestations, etc., etc. It generally
is kinda' stupid, but that's usually true for just about anything in those settings that actually adheres to an alignment -- anything that does
that is going to be mono-focused to a degree they start missing things. A pure expressions of
any of the alignments is basically full blown insanity.
You just have to think of those settings as, beyond the general hellworld thing, what amounts to battlegrounds between conceptual, lovecraft-style, eldritch gods that just happen to take a less immediately mind-destroying form in favor of a more insidious insanity dispersal method. You're not really dealing with
stupid, per se, as you are with
Other. Stuff that, when you get right down to it, is fundamentally inimical to life as we generally know it. You'll note well that most of the alignment planes in those universes
don't manage to support a baseline human population :V
Selfish Chaotic character would not go and randomly do evil stuff that would certainly cause his/her death, for one.
Well, sure, but what we'd consider lolrandom evillulz of self-destructive attention-grabbing in a sane, stable universe, is stuff that can very much literally provide unlimited cosmic power in these places. Capital-E Evil is something that has significant metaphysical and magical backup in these places. What would be guaranteed death in a sane world is very much
not in the hellscapes that most P&P RPG settings consist of.