Pro sports are (nowadays) highly specialized, highly optimized professions, where one millisecond counts. Whether it be though underlying genetic predisposition, or social opportunities/incentives (both discussed in other replies), it is not unlikely that one identifiable section of the population would have inherent advantages.
STEM (or similar endeavors) are no such thing and never will be. Progress in these fields require the entirety of human virtue (and perhaps vice) - over and above that which can be strictly measured, categorized, in-calculated or trained. There is no good reason why any part of humanity should be under-represented in these undertakings.
There's nothing really stopping anyone from playing or enjoying a game, and as kids back in the day we used to play for fun on schoolyard courts. The problem is cultural; we as a culture have not really valued sports as recreation, but as either professional calling or consumer activity.
Trying to argue from the outlier really doesn't work as you said, but its also more of a cultural issue that we really don't value participation in sport over production of it.
There is no good reason why any part of humanity should be under-represented in these undertakings.
So for you culture has no impact on an individual?
Why should a particular field of human activities represent equally all the subsets of human groups?
Individuals are part of groups and groups have their inner dynamics and features.
Why are they more male chefs with 4 Michelin stars? Should there be an equal representation of women? No.
STEM (or similar endeavors) are no such thing and never will be. Progress in these fields require the entirety of human virtue (and perhaps vice) - over and above that which can be strictly measured, categorized, in-calculated or trained. There is no good reason why any part of humanity should be under-represented in these undertakings.