Pacing a megadungeon

[King of Nowhere]

Did you mean "selfless" or "self-sacrificing" instead of "selfish" there? Because selfishness and intelligent self-interest rarely result in death, IME. Whereas being "kind", and wanting to take the bandits alive, eating (in, say, D&D) a -4 penalty to hit for dealing subdual damage, can result in a "stupid" death (or even TPK!) against opponents that otherwise wouldn't have posed a threat. That's the problem with choosing such a suboptimal path of "goodness" over pragmatic cowardice and self-interest.

And "paranoid" sounds like the kind of trait that keeps one from dying a stupid death - "I was playing perfect 5d Wizard Chess, to the point that even my Contingencies had Contingencies, and that's why I died" has said no PC ever. "Overconfidence" and "lack of paranoia", OTHO, have claimed many a noob.

disagreement here.
first, you specifically mention intelligent self-interest. well, intelligent selflessness is also rarely going to result in death, and if it does, you generally accepted the possibility.
being selfish leads to being isolated. being isolated leads to having no friends. no friends means nobody will bail you out when you're in trouble. and you'll have more enemies.
paranoia also leads you to distrust, which leads to losing allies.
stupid evil is as dangerous as stupid good.

"I was playing perfect 5d wizard chess, and then twenty high level npcs assaulted my fortress and overcame all my defences and there was nothing I could do, because I pissed them off, each one of them"

I mean, if selflessness wasn't actually good for your own survival in a variety of scenarios, evolution wouldn't have preserved it.

EDIT: in the case of talekeal players, they betray anyone in their selfish interest, and their paranoia leads them to chasing and killing any enemy that tries to escape. this will lead to harder fights, and nobody will surrend anymore, and they may not have a chance to surrender themselves the next time.