the economic (counter-)argument for higher taxes on the wealthy is that our economy becomes more dynamic and creative when wealth is more evenly distributed. you give more people chances to come up with something cool and ingenious with that capital. rich people get complacent and go after moribund ways to keep and expand their wealth.

plus, the wealthy have benefited more from the system so it’s fair for them to pay more for it. no rich person is mortally worried about their lives if their marginal tax rate goes up to 50%, whereas that would be perilous for the poor.