Went to public elementary, upper-tier non-religious private middle-high school that regularly sends kids to Harvard, MIT, etc. Everyone around here tries to get their kids into private school, especially if you have money. As such, most kids parents are doctors, lawyers, etc., middle to upper class. Socioeconomic and racial diversity is much lower compared to public schools as you can imagine. Plenty of these parents, imo, naively believe the private schools offer superior education. I didn't think the teaching was anything special, and paled in comparison to my college professors. What it did buy though was a select peer group, which is important as well. Kids with good homes, good upbringings with parents who somewhat care. I say "somewhat" because it seemed most parents were of the mindset that the school should take care of everything. Of course they'd go to conferences, events, etc. but I don't think most parents were involved in their kids day-to-day education. Also, private school seemed like an expectation if you have money, I think some use it as a status symbol or to brag or others think your kids are smart (which isn't necessarily true unlike college), and I think some ignorantly believe its what you should be doing if you care about your kids education. That's not to say the school didn't have problems. Drugs/drinking were common, kids still got in trouble, kicked out. I know some folks who since graduating have kinda faltered, some going to rehab (including one top-tier student), and so on.
I remember thinking how sheltered some of my classmates were, since I grew up in a lower-tier neighborhood compared to most. In hindsight I can kinda see how it creates further division b/w the rich and poor in the community and I tend to agree with the idea that our public schools (in my area) would better if private schools didn't exist. There was an elitism that existed that didn't sit well with me, even as a teenager, I'd be ashamed to say what school I went to. One thing I do realize in hindsight, that part of the hype around private school was college admissions for seniors, which sounds great on paper, but no one sat down with seniors to talk about careers, majors, money, etc. It was a competition to get into the "best" college, but plenty classmates ended up lost during or after college, figuring things out, jumping around jobs, going to grad school, etc. Plenty kids avoided our lowly State school for undergrad, but gladly went there for grad school. Some folks I know still are lost or aren't particularly happy where their life is, despite a 'good' career. Yet they took out huge loans for college or their parents paid. Some kids went to private college only to become a local teacher or police officer. However, our public schools offer career and college counseling. IMO, not everyone is cut out for or needs to go to traditional 4yr college, including private school kids.