And Terrence Tao who is quated was also extremely good at olympiads. As I see it, the olympiads are a good cost-effective way of identifying talented kids, they are in a way just IQ tests.
I think the point being made is that the converse need not be true: kids who are not good at these sports need not feel discouraged from pursuing mathematics.
Yep. Success in math contests is correlated with success in producing mathematical research/getting tenure/measure what you will. But if you sample math professors, you won't find that most of them were problem solving champions. (A large minority perhaps, and probably more in number theory.) The common factor is more likely that they really like doing mathematics, and have the skills needed to suceed in secondary aspects of the job.
I know plenty of very good mathematicians who did not participate seriously in this kind of thing. (Disclosure: I work as a mathematician at a research university.) I'm not sure why the only ones quoted here are mainly ex-winners. Indeed, while these competitions may have the positive effect of putting like minds together, it's possible that they have the negative effect of discouraging those w/o the aptitude for this particular kind of competitive sport (which is what it is), or who do not have access to the kind of coaching and practice that successful competitors often have.
