Social mobility is far better than in other parts of the world. Free to succeed and free to fail, it's a 2 way street.
Well, statistically, social mobility has been declining in the U.S. I know this goes against the grain of Americans, who like to think their country is the ultimate, as far as social mobility goes, but they're now pretty far down the list.
The fact remains if you put in the effort, you can get ahead. You need to actually attend school and finish with reasonable (not excellent) marks. You'll be guaranteed student loans and grants and placement at a university if you do this and then you're on your way. Learn to dress and talk like the mainstream, and people will treat you like a part of the mainstream. Talk and dress ghetto and nobody from the mainstream wants you near them.
The problem is not that you can't do it. The problem is the temptations put in your path to not do it. Unprotected sex, drugs, gangs, easy money, and a host of others, including the sense of inevitability so many young people in those circumstances feel, that there's no point in trying because it's hopeless. That's the big killer. School ain't cool. Cool is a shiny hand gun and big muscles and a reputation that nobody better diss you.