Every rule in our society is upheld with coercion. Even if we had zero taxation, there'd be plenty of other rules that people would be coerced into following. Without a democratic government, the rules that people are forced to follow will be the ones these billionaires choose. I'd bet that those rules are going to be a lot worse for the average person than current levels of taxation.

What we are now seeing is the end result of capitalism. Wealth concentration so bad that a few billionaires can take over and start making their own rules.