>If 99% of rich people don't participate in endurance sports, then it is not a characteristic of rich people in any meaningful sense.
That doesn't follow. If 1% of rich people do X, and only 0.0001% of non-rich do it, then X is very much a trait of rich people. It's not of most/all rich people, but it is predominantly of rich people.
Personally, I wouldn't consider anything that only applies to a tiny percentage of a group to be a trait of that group. You could say that being rich is a trait of people who participate in endurance sports, but not vice versa.
That doesn't follow. If 1% of rich people do X, and only 0.0001% of non-rich do it, then X is very much a trait of rich people. It's not of most/all rich people, but it is predominantly of rich people.