In a weird microcosm of your post, the first time I ever had the concept of communism explained to me - as in, how it might apply to contemporary society, rather than however it’s described in school textbooks - was by a guy in the year above me when I was 16. I can’t remember the context but he was definitely advocating for it.
I last saw him about five years after he left school. He’d become a corporate lawyer in the City.