They're arse-holes.

But seriously, I think you hit on it:

Education (or the lack of appreciation for)
Poverty?
Racism?
Single parent homes?
?????

Although I wouldn't really put racism in there...it plays some role (both ways mind you), but it's really a poverty/education thing. And because of that the inner-city "thug" mentality is to shun education and any legitimate effort to better oneself.

But the biggest factor is education. People need to be better educated...but we have to get them to understand that they need the education first, and that's a problem.