Also, going straight to comparisons of athletic ability and ethnicity is basically a hundred year old argument made by people you probably don't want to associate with.
Tech exacerbates this problem even further. How can you get anywhere as a kid if your parents don't have a computer, and neither does your school? And that's just one example.
That and luck are well over 90%, yes. Otherwise the scions of the wealthy would be vastly more prominent in sports with low entry barriers. In practice the most decorated Olympian ever is the son of a police officer and a middle school principal[1]. The best basketball player ever comes from a less distinguished background[2]. College sports specially chosen to be niches to maximize the chance of being a recruited athlete are so competitive the children of hedge fund managers routinely fail to get in that way[3]. The outer extremities of talent distributions are people who are staggeringly talented, hard working and lucky. Then they complete with each other and the ones who win are better than that .
[1] https://en.wikipedia.org/wiki/Michael_Phelps
[2] https://en.wikipedia.org/wiki/Michael_Jordan
[3] https://www.theatlantic.com/magazine/archive/2020/11/squash-...
By this logic we should expect the NBA, NFL, NHL etc. to look like a random sample of the US population. If the source subpopulations differ by even small amounts on mean or variance those on the extreme tails of distributions will look very different from the general population. So the ranks of men who have ever run 100m in under ten seconds are basically all black and elite marathon runners are about half Kalenjin, an ethnic group of fewer than ten million.