You’d be competing against multi-billionaires and huge corporations. It wouldn’t be enough, even though it’s a ridiculous amount of money for one person.
Changing the US would probably be impossible. Maybe changing your state would be possible. Changing your local community would be much more realistic.
Helping people get homes and food would likely help reduce crime.
Helping people get educations would help some people escape certain situations.
If you’re fixed on changing the US political situation and you think there’s a party that can change the situation, you can go with political donations. I believe whichever party spends the most money on their campaign is the one that wins more often than not.