Well, I suppose you could perform random shuffling. 50% of people will still end up with a below average outcome, though.
His point is that true social mobility would be literally hitting the random button repeatedly. It's obviously not a workable idea.
Someone has to lose, even if you perform a magical full reset once per year, in any given year half of the people will be below average.
The goal of course is that we make sure that everyone has a decent life even if they're not at the top.
I think you've jumped on his comment and assumed that he doesn't care at all about anyone who's not in the top N% which isn't a charitable reading.
Holding a 4-year bachelors degree puts you in about the top 1/3rd in academic outcomes (meaning you personally are 50/50 to be in the top 1/6th).
It's not for me nor anyone else to define your ceiling, but I would expect based on the limited data presented and, to the extent that academics is a predictor of outcome, that your outcome would be quite likely to be above the average. That you're engaged on news.yc is another generally positively correlated term I would think.
I hope those of us that didn't go to MIT like you have a place in this society.