The GP was pointing out that out of the small (relative to the number of college dropouts) group of Harvard MBA grads, there have been quite a few tech startups

The GP was pointing out that out of the small (relative to the number of college dropouts) group of Harvard MBA grads, there have been quite a few tech startups. You are right that any such correlation doesn't imply causality - maybe the MBA and startup success were both caused by a prior drive. But its an encouraging sign; that Apple and Microsoft were started by dropouts doesn't really change that.