You really have to wonder why people with every advantage don't succeed. 
The same reason black people can't succeed.
It's the same reason the "white thrash" don't succeed.
It's the stigma of growing up in an environment, a culture of failure, of no intellectual challenge, where brawn is heralded more so than brains, where there is no tradition of higher learning, et al.
Having poor classes, whether they are black or white, is a gigantic economic waste for a nation like USA.
Imagine if we could get 25% of the people in these social groups to finish a higher education. Imagine what that would do to raise the Gross National Product. Not to mention the drop in crime rate, likely health improvement, dental improvement et al.
Instead of playing the blame game, black people, white people, and everyone, needs to address the situation.
Because everyone would be much better off if the poverty was erased and replaced by properly educated people.
Can it be done?
Is it time for a 21st century version of the New Deal, but this time with Higher Education at its focal point?
I think it's a grand idea at least. The vision of getting most of USA's youth into higher education in 10 years could completely change the situation, and be a big step away from the racial barriers that do exists today.