Democracies make this impossible. Those people vote and they will bring into power politicians who will tax productive people to pay for their own survival.

My country is heading down this path as we speak. President literally gave a speech where he asked something like "who will ensure the survival of the millions of useless people created by technology?" They're obviously going to make us pay for it. The actual billionaires will simply leave before they get taxed, of course. Whoever stays gets to foot the bill.