> I am very keen for levels of taxation (and the closing of all the loopholes) that would force billionaires to liquidate significant percentages of their assets to pay taxes as I think it will encourage them to work a bit harder. After all if they managed to become a billionaire once they must be very clever, right?

Even almost all their "assets" are stocks in the companies they created? Would the idea be that the founders of these companies should lose control over them?