Because they buy houses to rent back to me, they get the opportunities to invest in businesses before me, and they use their money to influence politics to ensure they hold on to their position. They push governments to privatise healthcare making me pay more for it, which they profit from, and that means I'll never have any sort of financial security. I have to live my entire life hoping I never get seriously ill. They buy laws to break the power of unions and collectives. They hoard money in offshore accounts which starves the government of tax revenues so I live in a society with underfunded police, unfixed potholes, and failing education while they* get all those things because capitalism provides those things to those who can pay.

Would that somehow suddenly change if somebody at the top had a quadrillion dollars of spending power?

If they used that wealth to influence the way society works, it would mean I live in the world they want. I don't want to do that.

* Actually I don't, because I live in a country with universal healthcare, but you might have that worry.