I think I get the question, and the answer is no. Being poor is very expensive, and everything you do has added costs that you can absorb or not deal with when you are middle class or above. The fees for check cashing in this thread show an example of that.
Living on the street, and you get sick, you are screwed. Since money and food are scare your body is under stress, and being exposed to the elements, you will get sick. One hospital bill with no insurance and you are in permanent debt. One arrest and trip to jail, and now you have a criminal record which makes it harder to do everything from getting loads, renting a place to live, employment,even volunteering; some volunteer organizations won't take convicts. Then you have no transportation, miss a single court date and now you get fees, fines and warrants leading to a spiral you don't get out of.
Maybe 4-5 people out of every 1000 make it out; it happens so rarely that the successes get on TV, book deals and movies of the week. Can it happen? sure. Does it? The odds are very much against you.