I would also argue that the intersection of people who become quants / found successful startups and did so despite having a real shot at becoming a professor is pretty small.

My only real data points are my own graduate school experience, but I haven't heard of anyone who was on a path to success in academia who didn't continue on down that path, or at least give it their absolute best shot before moving in. By success I mean maybe a post-doc or two followed by a reasonable shot at a tenure-track position at a decent school. This restriction is made in the same way that (I am assuming) pg is only referring to quants at decent firms, and startup founders who at least have an idea they can get off the ground. I seriously doubt that any kind of conformism at say, an ivy league institution, is because people who would have become profs there chose not to.