TFA and other commentors have some points, but I believe it's much simpler than all of the above:

Doing a thing is a different skillset than teaching how to do that thing. Nothing more to it.

If there was a self reinforcing loop where greatness begat greatness, it would be everywhere: every sport, every politician, every martial art, every resource, every industry - for centuries, millenia.

Greatness and teaching greatsness are merely correlated in the best case, and are just as often counterfactual.