I wonder if age makes a difference here (i.e. how E is your R?)
I'm in my mid 40s and probably "peaked" in my career (at least, hit the top rung of the ladder in my particular field) 10 years ago (got the final promotion 5 years before that, but I'd say it took another 5 years to feel I was really doing the role comfortably and well). So from a professional point of view I don't feel I have anything to prove any more (don't get me wrong, there are more senior jobs - but those are proper "leadership" type roles that I don't have any particular aptitude for, meaning they would be very energy sapping for me and I don't have any appetite for them, given I would probably never do them very well even if I could get hired to one).
The other advantage of being older is that several of my friends are not working or at least not working full time. Either they've gone from corporate to smaller freelance gigs, went on maternity leave and never felt the need to go back, or I recently found out that one of my University friends actually pulled the plug on a big corporate job and retired (I'm not convinced he won't go back at some point, but that's certainly his story for now).
Having kids also helps because it is a kind of obvious ticking clock: they won't be young and want my company for ever, so it makes sense to pull the plug now unless I have very good reasons for staying.
Of course, I'm still prevaricating about actually pulling the plug. I've done it very slowly and probably won't be fully out before Easter (a full year or more after I originally intended, pre-pandemic). That's been more about my feelings of responsibility to certain colleagues, projects and clients though, rather than feeling that I actually want more stuff or more prestige. Plus a generalised fear of change - but I don't think that's what you're talking about!
I think though that retiring in my mid-30s would have been much harder, even if financially I was in a very strong position, due to some of the issues you identify around guilt of a "wasted" education, or wondering if I could go further in my career in X, Y or Z way - and just far fewer people on a similar path in my cohort.