I won’t touch this one. Other than to say that is in our genes. As a species we are successful in part because of are ability to compete. And part of this is the underlying desires to have our own personal gene pool survive. In the deep dark past, the introduction of a new variation of species was a threat to the existing pool. So we developed an underlying predisposition to eradicate it and protect the existing pool. These days, the underlying spark is still competition, although it is for other things now. But take people today and add some stress, and many will tend to fall back onto the old hard wired genetic traits. Also there are some who are just horsesasses too. The part that really bugs me is the political correctness crap. It often prevents a meaningful dialogue and this hampers society as a whole.
Another thing that really bugs me is the misuse of terms that are often used in these types of discussion. An anti-Semitist would hate Arabs and Jews alike. Both groups of people are part of a larger group know as Semites. But it amazes me to see one Dr. Soandso after another pervert the term to advance a political agenda. These days it is most often applied to the acts of racial cleansing perpetrated by the Nazis, and the problems in the Middle East. The Nazis were anti Semites, but the Palestinians and other Arabs are not, they just hate Israel and anyone that supports Israel. Of note here is the fact that the Palestinians have little or no claim to the area known as Israel today. Its real name is Assyria, and in modern time it was the property of the Ottoman Empire (1280 > 1923) and then past into Egyptian control (Who were under the thumb of the English). I would think that any claims prior to 1280 would be beyond enforcing today. Never in modern time was Palestine a Nation or State. Palestine was not even a province under the Ottomans.
Ottoman holdings So what we really have is competition again. I guess people are just born to it.