When people complain that neoliberalism is a meaningless concept, I should point them to what has happened to the top rate of income tax since around 1980, not just in the US and UK but elsewhere. (Source HT Marcel Fratzscher)
There is a final argument for high tax rates at the top which seems particularly relevant to the US and UK at the moment. If you have a political system like the US where money easily buys political influence, you will find some of those who earn very high salaries trying to do exactly that (some references here). You can create the kind of plutocracy I discuss here. Because money can also help to buy votes, that plutocracy may also be able to continue with democratic elections without in any way threatening the plutocracy. Even when you have laws limiting the amount that can be spent on elections, the UK shows there are ways for the rich to get around that, particularly if they control large sections of the press.
“An extreme concentration of wealth means an extreme concentration of economic and political power. Although many policies can help address it, progressive income taxation is the fairest and most potent of them all, because it restrains all exorbitant incomes equally, whether they derive from exploiting monopoly power, new financial products, sheer luck or anything else.”
“most rich people I know would have been happy to spend vast sums of money to keep Mr Trump out of the White House. And many tried. The Trump phenomenon is not an argument that the moneyed elites have too much influence on politics. If anything, it is an argument that they have too little.”