To play gator's advocate, many of those slaves were not allowed to learn how to read or write. We're five generations removed from black folks who were prohibited by law from learning pretty much anything besides picking cotton. Fast forward to 1900 and still only 50% of black men aged 20-64 can read and write. By 1930 about 20% of all blacks aged 10 and up are illiterate. It's considerable improvement, but we're only about 70-75 years removed from a full fifth of the black population not being able to read or write.
It is not surprising, then, that many blacks, and the impoverished as a whole, continue to live in a way that makes middle-class white people raise their eyebrows. Their way of thinking about things is vastly different from the way you or I may think. You and I are future-oriented in our thinking. We invest, save, prioritize around the future. Our parents raised us to think about the future, it's all we know. The impoverished as a whole are present-oriented. Their lives revolve around what they and their kids are going to eat tomorrow, where they'll find decent winter coats and boots for this winter, where the money for utility bill that's due next week is coming from, etc. Everything is prioritized around the present out of necessity. Kids fall in with gangs and the drug trade because they provide immediate safety and financial security. They won't live to see 30, but hey, at least they'll have friends and some cash.
So the way to change culture is to change thinking. The benefit and safety net type programs are in place so that impoverished folks can worry less about the present and invest and work hard towards the future. But there's no incentive or motivation to work and invest towards the future if there's no education and no end to the benefits in sight. They keep thinking about the present and often never even see a way out even though it's there for them.