You get to keep only enough to maintain a very modest lifestyle in a low-cost-of-living area, the rest of it has to go towards improving the world in some way.
Edit: Given the previous rules that you must maintain a very modest lifestyle in a low-cost-of-living area, would you rather choose to opt out and not have the money at all?
That sounds pretty good too, yeah. The program could be expanded to include safe spaces/training for teenagers and such too, probably include a rec center that always has stuff going on for them to participate in, etc. At that point it turns from a housing/job training project to basically a community, built around safe spaces, opportunities, and education for the future.