Since money always flows from the poor and middle class to the upper class, who owns the means of production and distribution, the rich has to be taxed more to keep them from putting the medium of exchange under the mattress which stops the moving of goods and services which has real value. Money only has real value when it is moving goods and services.
The rich hoard the money supply in off shore bank accounts, in gold and silver coins and stock accounts. If they would only spend the money every one would benefit, and they would get it back with a profit. Why are rich people so stupid?