Is it? We know of two notably successful Harvard dropouts: Zuckerberg and Gates. While their success most likely hasn't been anywhere near as spectacular, I'm willing to bet you know dozens of successful people who graduated from state & small private universities.
Both also had very upper middle/upper class backgrounds.
Conflating one spectacular success with all [Harvard] dropouts is a silly comparison.
Better to win the megabucks than the $5 scratch-off ticket.
What's your point? That being an enormous outlier is sometimes a great thing?
Its like law school-its better to graduate from Stanford at the bottom of your class, than from Santa Clara University at the top. Prestige matters.
And to combine that with an upper middle class background (like Zuckerberg)
I think Zuckerbergs upbringing has more to do with him as a person rather than the university from which he did not graduate.
His Facebook unicorn success was hugely dependent on the Harvard classmates who hired him to start the project he branched from, his Harvard cofounders, and his Harvard employees. He couldn't have done that at UMichigan.