You don’t even need to tax it at 80% because if you did billionaires would move elsewhere (see: France). But … you could simply tax it at the same rate that you tax, say, secretaries or accountants or teachers. The problem is that most income for the wealthy (myself included) comes from stock gains or dividends which have lower tax rates than income. And the uber wealthy (not me) pay people to offshore their income and avoid paying significant sums of tax. Aside from this one comment — thank you for writing an excellent response!