“Outlier” is extreme. A significant portion of black Americans are in the middle class. The legacy of historical racism is significant, but exaggerations don’t help anyone.
Also if you want to look at the wealthiest 1% as outliers, only 3% of these outliers are black [0]
0: https://www.nytimes.com/2012/01/15/business/the-1-percent-pa...
What is the reason of that?
All this data can be found from the source I linked to above.
https://www.npr.org/2017/05/03/526655831/a-forgotten-history...
Think about it - in most cities the entire shape of our urban landscape is defined by the movement of white people to avoid living near black people. Similarly, the reason public transit in most of the US is near non-existent is b/c people do not want buses and trains bringing 'other' people to where they live.