If you or I had started swimming at age 4 and had top coaching, There would be little hope against a genetic freak like Phelps. Also, the existence of him and many other slightly less extreme genetic freaks means that it would be a very, very poor idea to invest time in trying to become a great swimmer. Unlike them, we'd have no career prospects.

The author was right. It's much better to invest time and effort into a pursuit where you have an advantage. And it follows logically that if you don't have any natural advantages, then you should stay the heck away from winner-take-all professions.