I don't know how relevant it is to generosity that the rich give away a higher percentage than the non-rich. Gates and Buffett could give away 99% of their ear

I don't know how relevant it is to generosity that the rich give away a higher percentage than the non-rich. Gates and Buffett could give away 99% of their earnings if they wanted to. If I did the same, I would be more in need of charity than those I was giving to. It would make more sense to deduct an amount similar to the "consumption allowance" in sales tax proposals to account for manditory or quasi-manditory spending like food, shelter, health care, etc, and judge only income above this level.