Past a few million, wealth has basically no correlation with consumption. So to the extent that economic inequality is about unequal access to consumer goods (vs unequal numbers in a brokerage account), those high incomes are not a factor.

But they have an important indirect impact: wealth correlates with power; if you're richer, you can control more businesses, and run them the way you'd like. Thus, high marginal income taxes keep the old guard in power longer, and mean that ambitious people with new ideas take longer to take control.

High income taxes and capital gains taxes will mean that proportionately more of the world's companies will be owned and run by Rockefellers and du Ponts rather than Zuckerbergs.