Interestingly enough, the ultra rich would probably like to move to a sales tax model too. As a fraction of income, I'm sure that billionaires do spend less than any of us.

For a sales tax to derive the same amount as an income tax, it would have to be very large. Warren Buffett said that his effective income tax rate is around 16%. For a sales tax to be comparable, it would have to be, say 32% and Buffett would have to spend 50% of his income on taxable goods.

The author does mention a wealth tax, but does not really elaborate on that.