Private schools--or neighborhoods with a good school system--are basically about segregation. Every single black child I've ever seen--with one notable exception--had a super arrogant streak, in one case it was a one-time thing, in every other case like holy shit (though another one I sometimes had good conversations with, it just varied). Like out of nowhere, spitting in my path in US--that's racial bullying on their part, they're trying to impress white boys--literal white boys, white males under the age of 18--that they can even intimidate white men. So then what? What's the endgame of those underage black boys? What are they trying to accomplish? Whom else are they trying to impress?
And so then you just want to avoid them, because nobody can punish them without undergoing that which Americans and especially Californians are most afraid of--being accused of racism.
California is built with this form of segregation in mind--highways, no sidewalks, no public bathrooms, extortionate rent (huge percentage of income, 40% is common) with the homelessness that is its direct consequence, crazy zoning (you could economically build 60-story skyscrapers anywhere in Palo Alto), concrete everywhere with many places inaccessible except by car, hospitals out to fuck you, firmatage, terrible public transport--all out of fear of harm from minorities which can believe it or not be out to get whites--have that specific intent of harming whites, and they get convicted for hate crimes but those crimes never make the news--which they never punish, only prevent.