Also, even if you did hypothetically spend 100% of your money, and all of it was taxed at 10%, with a 50% effective income tax rate you'd be having a 55% overal

Also, even if you did hypothetically spend 100% of your money, and all of it was taxed at 10%, with a 50% effective income tax rate you'd be having a 55% overall effective tax rate - the money taxed for income isn't also taxed for sales. So you can't add tax rates like that.