I guess I am asking more on a national and/or cultural level than a personal level. Why do people waste their time and energy hating each other?

I recently came across this[0] Wikipedia page on something called "Sinophobia" (which is a term I have never come across) and was actually very shocked at the length and amount of data presented in the article. I then clicked over related articles regarding Muslims[1] and Hindus[2] and found them astonishingly long as well. I just don't understand why anyone would waste their time and energy and brainspace hating another group of people.

(For the record, I am a boring white dude, and have no feelings towards any particular race one way or the other. I live in a city where many cultures exist comfortably. Maybe that speaks to my bewilderment. I've seen actual, overt, real-life racism happen maybe 10 times in my 35 years. Also, I really hope this doesn't turn into a complete shit show.)

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[0] https://en.wikipedia.org/wiki/Anti-Chinese_sentiment [1] https://en.wikipedia.org/wiki/Islamophobia [2] https://en.wikipedia.org/wiki/Anti-Hindu_sentiment