About 3% of humans are born psychpaths (roughly: they have no empathy hence only care about themselves).
One would naivelly expect that only caring about yourself would be a winning strategy from a genetics point of view and hence over time the whole of Manking would have become psychopaths as the ones with such a natural advantage were more successful at surviving and reproducing than the others, yet that’s not at all the case and only a small fraction of people are born psychopaths.
My personal explanation for that is that psychopathic behaviour is only a genetic advantage if most people around are not that - or, transposed to to economic terms, being a rent-seeker only works if most people are producers and doens’t at all work when most people are rent-seekers.
I expect that in our evolutionary past, whenever a tribe/group had too many psychopaths without some kind of mechanism to kick them out or force them into cooperative mode, it eventually collapsed and ended up removed from the genetic pool hence why in millions of years of evolution the supposed superior behaviour of caring only about yourself didn’t end up dominating the human genetic pool - the “threading of the needle” for the survival psychopathy as a behavioural trait in the gene pool was a balance between that behaviour expressing itself often enough to reproduce and remain in the gene pool and not so much that there were too many such individuals in a group causing it to collapse.