Stop thinking about taxes as a way to fund the government.

Money in the long run can buy anything, including political influence. There are no regulations that can effectively preclude this. (And empirically, America over the past 40 years has seen moneyed entities successfully re-align politics and economic policy with their interests -- this was entirely predictable). An unequal society therefore cannot be a democracy. If you believe in democracy, then you necessarily must believe in wealth redistribution. (In fact, I argue that any person who believes that the American Revolution was justified, for any non-trivial reason, will likely find that those the same non-trivial reason could be invoked to reallocate wealth away from today's wealthy.)

Counterarguments to this view (i.e. a different top-level value than democracy / meaningful sovereignty over the society in which one lives) might invoke utilitarianism: an unequal society potentially produces "better" outcomes if capitalism is allowed to run unrestrained.

But a problem this argument encounters is who gets to decide what "better" is? All systems are economic in the long term, including political ones. A good framework for understanding is that a society in the long term is not "one person one vote" but rather "one dollar one vote." Today's preferences are dollar-weighted. Those with money decide what is better. The economy serves the average dollar's interests. And the average dollar's interest are the wealth-weighted preferences of society's members.

We started with an income tax to fund the government. But today our most pressing issue is not funding the government, but not having an oligarchy. Wealth is the thing that most needs to be taxed in order to allow for any semblance of democracy. Analogies drawn to income, though interesting, are meaningless.