I remembered that Cuban was on record for saying & doing this & that link was the easiest to source from because so many people know who he is. I wanted to highlight the deed itself. More recently, was the open letter written by over 250 billionaires & multi-millionaires pleading to be taxed more than they currently are.
As you say, you know it's almost pitchfork levels when the letter, which was read at WEF in Davos, says

“Our request is simple: we ask you to tax us, the very richest in society. This will not fundamentally alter our standard of living, nor deprive our children, nor harm our nations’ economic growth. But it will turn extreme and unproductive private wealth into an investment for our common democratic future.”

According to the article, "Imposing a 2% tax on the world’s billionaires alone would raise almost $250 billion annually"
Question is, why are governments so reluctant to grant them this?