I never went to parties like this. I wasn't socially marginalized, I just wasn't one of the popular kids. Popularity at my school was closely tied with wealth and family status. A relatively tiny group of people lived this sort of life.
I look back at high school and see several popular groups. Did one rise above the others? Not in an obvious way.
Like you said: some were from wealthier families, some were the athletes and their groupies (no surprise). But I went to parties of all shapes and sizes - some in those groups I just mentioned and some in other groups. Didn’t really matter that there was a premier group of socialites.
Then when the popular kids were bored occasionally they'd end up at our shindigs