The government uses taxes as a way to reduce monetary inflation. Think about it: issue bonds, borrow Fed money, spend, the monetary inflation affects everyone equally in proportion to their fiat holding. It's regressive. Then, collect taxes and destroy some of the printed money by paying down debt. You get to reign in some of that inflation and also decide who benefits from it the most. Progressive taxes are supposed to ensure that modulation of inflation benefits the bottom people more, who are affected by inflation Kore because they don't hold Jon money assets. Of course, we always see ways to avoid taxes for people with complex finances, so it never works that way.