You obviously didn't read the thing. 20% is not on wealth. The argument in the piece is that 1% on wealth is the same as 20% on income, and therefore 1% on wealth is obscene.

Please read before making replies that don't make sense in context. When I refer to 20% I'm referring the PG's characterization of a 1% wealth tax as an effective 20% income tax, not a 20% wealth tax.