A large percentage of "normal" people, ie close to the median will see those famous people as potential role models. When their internal pattern matching engine detects that 90% of those belong to a class they do not identify with, that can cause a crisis of faith in their own dreams, self-esteem, etc.
At that point, there is no comfort to be found that 90% of the people at the very bottom belong to the same class as those at the top. Not only do they not see those at the bottom, they do not WANT to see them.
So if someone tells a story that explains the difference as a result of oppression, it becomes really tempting to chose that explanation, whether or not it is true.
Oppression may indeed be the main reason for differences in many cases, but even when it is not, it will be attractive to believe it is.