Why are people so mean?

At this point I would like to throw to our resident specialists on such matters Gramps, Semich and Juan Peron Adolph Eichman Eva Garafolo. Some say the NYT has established why over meany years  - but I Douthat My own position remains that about 33.3 % of people will always be mean no matter what. I do what I can in my spare time to try and minimize the harm these meanies cause. No don't thank me - a few thousand Btc will suffice. Tia.