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?
Kick them in the nuts (or the stomach, in case they don’t have nuts), because relying on individuals with money to solve our problems is one of our fucking problems.