You know why and I know why. The crony game, and tax cuts or tax increases, works for them. Indeed, increasing the size of government often helps these bazillionaires directly.
Plus as Varney explains below, many of these people don’t make much “income” (in relative terms). They are just rich. They don’t care if the bourgeois business owners and professionals (who earn taxable income) are taxed. If anything a nice healthy income tax helps keep the “new money” in line.