the reason statistics like this exist is because we’re looking at a group of people who pursue the most challenging and ambitious thing of their generation. and at the time, grad school was that thing
now there are new more interesting problems to tackle and a lower barrier to entry
so that statistic is just correlation, not causation
school did not make these people successful, they went to school because they were ambitious, and willing to take on the most difficult challenges.
that trait is the most relevant predictor of success in any field or endeavour.
“I think the more impressive stat is that 63% of CEO's went to Grad School!”