I think you missed my point. Your post suggested that the top 0.1% are all at basically the same level (so that "the number hours of study and practice [would] become a significant determining factor in success.") But there is as much of a range of ability in the top 0.1% as there is in the next 49.9%.
I didn't miss your point, but I think you're misunderstanding how distributions work.
Assuming a distribution of talent that conforms perfectly to statistical odds, there won't be any +6 or +5SD students in this hypothetical competition, because they're too rare (1:1 billion and 1:3.5 million, respectively). You'd have 4-5 students of IQ 160, and about 20 others or so who are within +/- 5 IQ points of them, all of whom are close enough in cognitive ability that it has a negligible influence on the ultimate outcome. Other factors become more important.
