(I doubly distrust Thiel in particular on this, because not only did he not take this advice himself, but he also has a decades-long political feud with what he views as the too-liberal political climate in higher education, so would like it to be bypassed, regardless of whether he honestly believes it's a good choice for the kids in question.)
His main beef with academia is that he feels it's one major impediment to libertarian politics, so he wants as few people as possible to be exposed to it. Perhaps he also now genuinely believes that finishing his two degrees was a mistake, and it's actually in kids' own best interests to drop out of school. But I'm skeptical that that, rather than politics, is the real reason, as I usually am when someone's professed beliefs: 1) don't match their own actions; yet 2) conveniently match their politics.
Which is kind of ironic because universities overloaded themselves with libertarian professors (some with very flimsy scholarly credentials) in the last ten years in order to suck up to the Bush administration and the right wing donors that are getting more and more important.
But of course libertarians are not happy to have some professors in universities. After all universities offer tenure and independence of thought, etc. They much prefer to have no universities and have all scholarship done in "think tanks" where "scholars" follow orders and get fired at the first sign of disobedience.
Holy random statement, batman. Do you have a citation for this? The idea of libertarian professors being a plus to the Bush administration makes effectively no sense whatsoever.
Makes dropping out to pursue a startup a low risk / high uncertainty bet.