Take a software engineer, take away their house, job, and all of their money so they are homeless and have literally nothing ("broke"): how quickly can they reach a stable self-sustaining state again?
Probably pretty quickly:
- Ask family for help (they are anchored in a higher place to help bootstrap you up again - borrow some money, temporarily move back in with parents, etc)
- Get a new programming job
- Build a small nest egg
- Done, back to a self-sustaining state in a short time frame
Now take a kid from Baltimore who dropped out of high school and who has no skills. Repeat the scenario
- Ask family for help (they probably aren't in much of a position to help - they can't pull you up when they aren't anchored in a higher place)
- Get a new job (good luck when you have few marketable skills. The high(er) paying jobs for people with no marketable skills usually involve selling drugs/sex)
- Can't build a nest egg easily
Poverty (in the USA at least) is mainly a product of your family situation and your knowledge/marketable skills. If you have an unstable family and no marketable skills, escaping poverty is extremely difficult without an external actor helping to pull people up.