Even if "only" 10% of elite kids go on to become elite adults, 10% is orders of magnitude larger than the base percentage of adults who are elite athletes, musicians, etc. This doesn't sound "uncorrelated" to me so much as "not as strongly correlated as one might expect."
And describing something that happens 10% of the time as "rare" sounds a bit weird, like referring to left-handedness (also about 1 in 10) as rare.