It's not even as if it's exclusively about black people, the term "white trash" clearly doesn't apply to the black residents of trailer parks.
One other thought, if you want to strip away hope from someone a good way to do it is to get them dependent on welfare. Before long they realise they can never provide for themselves, at which point they are pretty much enslaved for life.
I read an article some years ago that compared a slum in rural India to a council estate in Glasgow. A council estate is social housing, often associated with the less desirable elements of society (partly because it's increasingly rare for anyone else to qualify for it). As it said, in the slums people didn't have time to waste their lives using drugs because they had to scavenge on trash heaps in order to survive. It's easy to argue that it's demeaning but it gave them a purpose in life. The occupant of the sink estate had no such hope - they were given money and effectively barred from working, so there was less and less reason for them to get up in the morning, less and less hope for the future, and so it's hardly surprising that before long all they wanted to do was find a way to dull the tedium of life. They didn't have enough money to do anything but had all day every day to try and fill.
When I first graduated university and claimed welfare pending finding my first job one of the declarations I had to sign every two weeks was that "I did no work, paid or unpaid". At least back them you couldn't even do volunteer work without risking losing some benefits.
With regard to the black population, I'm not sure that I'd use terms like "political hate" quite so freely but I suspect a part of the issue many people have is the sense of a double standard. We're supposed to be blind to race but every which way we turn people (usually those on the political left) want to focus on race. We can have special associations for black people but a comparable association for white people is deemed racist. If a white man attacks a black man the assumption is that it is racially motivated but if the roles are reversed it's just one of those things, or even justified on the basis of some perceived historic wrong, even though the white man never owned any slaves and the black man never picked any cotton. It's hardly surprising that people dislike a double standard, nor that they don't see a double standard as being an appropriate way to correct a past double standard.
