The author of ZeroMQ wrote a book on recognizing people like this, and more importantly how to get yourself out of prison they’ve put you in. The action plans have helped me. The lucky ones in the NYmag article here did many of the things he recommends. Free PDF here, look for the hard to find “read” button. https://www.gitbook.com/book/hintjens/psychopathcode/details
The author talks of psychopathy as an "adaptation" and not a "brokenness" in an individual ... but the adaptation so far mentioned is only in the sense of "the relatively small number of psychopaths is adapted to prey on other humans". I suppose that having too many psychopaths would render human trust very frail and would make a society prone to failure (and so be a negative pressure) -- so psychopathy can only occur within limits to be successful.
I wonder though whether there's another use for psychopaths: when a society or humanity at large faces a "bottleneck event" where extinction is very possible, the psychopaths "rise to the occasion" and do all the nasty, non-empathetic, distasteful things that a society needs to survive in those weird situations.
If so, then, ... psychopaths are harmful to individuals and society, until they aren't.
EDIT: actually, there's the brilliant Marlon Brando speech in Apocalypse Now (https://simonamooon.deviantart.com/journal/Apocalypse-Now-Ho...), where he describes bastards with empathy, people who love their families yet are able to perform the unthinkable atrocities [on their family] to win. So these folks are the opposite of psychopaths -- they do terrible things when necessary and doubtless feel the anguish of it.
EDIT: in other words, psychopaths are society's ultimate catastrophic re-insurance, the last resort.