We could increase the estate tax and capital gains taxes. They're much harder to avoid, the focus purely on income tax is the problem.
Because for some recipients, especially for the non-rich, these are non-repeatable, you do need to add some handling to the regular income tax system to address inconsistent incomes with multi-year smoothing mechanisms to make taxation of those kinds of income fair, but that also makes taxation of variable regular income more fair, too.
When these laws are passed, will assets be sheltered by accountants?
I know a Bitcoin millionaire. He avoided capital gains taxes this year by upgrading his Jeep. The money that would have gone to taxes, he used instead for upgrades, because of a loophole that permits upgrades to be taxed at a much lower rate.
They’re smart, the rich.