The thing that really scares me though is the way the problems change at the higher levels.
In case you find yourself in the situation, tell your employer. It may sound awkward to them at first that someone wouldn't want to be promoted, but in the end it is in their best interest to keep employees who ARE good at doing their jobs, instead of creating a situation where the same employee is suddenly no longer able to do a good job. This is no shallow talk by the way, but a well-documented, scientifically proven effect called the Peter Principle (which basically boils down to "everyone gets promoted until they reach the point of maximum incompetence and then get stuck in that position")
We as a society are trained to percieve "climbing the corporate ladder" as the main/only goal of working jobs with a hierarchy, but there is absolutely nothing wrong with staying at the level you're comfortable at. ;)
Ohh okay. I really misunderstood your point then, but thank you for clarifying ;)
Failing at something is not the end of the world. Sure it sucks at first, and possible setbacks in life aren't exactly cool either, but you DO sound like someone who refuses to stay down whenever life decided to knock you down, and that is something not everyone can do. That requires an inner strength and determination that a lot of people simply can't muster.
And you know what? Your idea of working in the social sector sounds like an excellent goal - it IS a hard job with little pay, but since you fought your way up from the bottom already, you have a completely different, deeper insight into related issues than someone who knows homelessness and its struggles only from a textbook. You will be able to understand clients in similar situations on a completely different level, and they in turn might be more inclined to trust your advice. You might be able to actually help people that simply fall through the cracks elsewhere.
Good luck, friend. May your spark never fade.