It wouldn't matter, because the ultra-wealthy generally don't have much income relative to their wealth. Elon Musk (in the article listed at $817B of wealth) was reported to have had $1.52B of net income between 2014 and 2018, and had no taxable income in 2018. 95% of $0 is still $0.
The ultra-wealthy's wealth doesn't grow because of income (as the tax code defines it). Trying to tax income to redistribute their wealth (or even just slow its growth) is not going to address wealth inequality.