And since we can't all be superstars at X, only the people that are superstars at X should bother trying?
I don't think this is true. Most importantly, just because one's performance at something is not among the best doesn't mean one cannot find enjoyment in it (not to mention the people that are just good, good enough for employment in it, or even especially bad at it compared to others). And in life finding the things that are most enjoyable is probably the one of the most worthwhile things you can do (at least if you attribute any value to happiness). With programming and mathematics in particular, it is not always obvious that you enjoy them from the outset: how the subjects are presented can dramatically affect one's enjoyment of them, and there is often a hurdle you need to get over in order to discover the pleasure of participating.
This was especially true for myself: up until my first year of college, I hated mathematics and most intellectual pursuits. Then I had an enthusiastic instructor in college that (among other things) approached mathematics from the "pure" perspective rather than the "applied" and to say the least it was life changing. And from mathematics I learned the joy of learning for its own sake rather than simply for its "utility", and this blossomed into a passion for many other subjects I would have never dreamed I would enjoy. Now I spend the majority of my time on them (to many's confusion and sometimes frustration), but just imagine how much better my life could have been had I experienced such a teacher when I was, say, 8 years of age. On the other hand, perhaps another "authority figure" of my youth would have come along and shattered such a passion anyway with a statement like "a genius will accomplish more than you ever will, common man, so don't waste our time"
And, not that this was being argued, but I don't buy the argument that "All people that are interested in X naturally gravitate toward X regardless of all other external factors." In the case of programming or mathematics, such an external factor might be an anti-intellectual culture (such as in the U.S., Brazil, etc etc) or ignorant backwaters stuck in their own miniature "Dark Ages"--where e.g. deep-set insecurities or prejudices are cultivated.