Unless I'm mistaken but we didn't have any billionaires a century ago. That's called inflation.

I don't see what is wrong with having many billionaires. That's something to be proud of, it means we are a country that creates wealth. American households are worth about $64 trillion collectively.

My point bringing up the 20% figure is that our government has tried taxing people more, but usually when it hits the 20% of GDP threshold the taxpayers melt away. We saw that recently in Oregon. It's not a constructive policy.