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?
Best that I can think of would be to create an endowed institute of political scientists, psychologists, neuroscientists, linguists, et cetera, dedicated to studying and developing ways to counter right-wing populism, and de-program people who fall under its sway.
Let’s congratulate you for being the only poster that did not want to go on a killing spree. If you want to change the world, you can do that by killing people. If you want to improve the world and start that with killing people you will never succeed. Thanks for that.
Leftist fascism killing people is not better than right wing fascism killing people. In the end everybody is dead and nothing is better. People after the second world war understood that. We have forgotten that and start looking for blood again, just to learn that expensive and painful lesson again.