The argument for taxing the Rich has never been about practicalities. To say that the rich should be taxed more by percentage is to say that there is a moral dimension to wealth, and that dimension is inequality. More taxation because of inequality implies that inequality is wrong and immoral.

The American wealthy do not see themselves as an aristocratic class, even though they demand social status, opportunities, trappings, and legal exemptions such things give. If they were for sale, they'd buy Noble titles and still not see the difference. It's true that poor Americans see themselves as potential millionaires, but also every millionaire sees himself as a humble workman.

Putting the burden on taxation on higher wealth is a direct attack on that self-image. It directly calls them out as different, and puts obligation on that difference. That difference is rooted in a moral question that can only realistically be answered with The existence of people like you isn't right.

It's an attack on their very existence. That's why they react so violently. They want the benefits with none of the obligations. They want to be the same as you, but better than you. Should that surprise us? The laege view history of the aristocracy is the slow whittling away of obligation and amassing of wealth and power. Any hiccup in this path is just a new aristocracy bribing the masses with temporary gains to insert themselves over the old bosses.