>>4812654There was a theory I heard about psychos being useful for crating hierarchy. Psychos are more willing to launch attacks on neighbors for selfish gain, in turn creating an in-group preference that would further heighten a society to reach new levels.
Without psychos there's a chance we would be too egalitarian to advance at the pace we have. On the other hand there wouldn't be as much conflict and deception. There's a trade off to be had.