I think too there are differences in professions. For example there are only so many spots in the world for a great pianist and there is a finite set of pieces to be played - plus a finite audience. That means that to have a career as a pianist you have to be beyond exceptional. You also have to really, really want it and be exceptionally single minded about it. And of course one of the things that separates truly great musicians from the *only* brilliant is musicality - that mysterious quality that turns beautiful playing into something sublime and is basically unteachable. One can tiger mom one's heart out, but it'll only get a child so far in this context.
In other areas of excellence this remains true to an extent, but to a much lesser degree. There is room for top scientists across a number of different fields, similarly while there might not be a career directly in philosophy or history it can be applied across disciplines. There will always be limitations in terms of numbers at the top of any field, but in disciplines beyond music and sport (which require techincal brialliance but where, ultimately, you're repeating the same thing in perhaps slightly different ways) - there is room for imperfection because that actually still contributes significantly to the knowledge base. Which to my mind opens up an infinite number of paths to a successful life - however that is defined.
