I just want to point out that billionaires don't just magically create more money for charities. Someone had to lose that money.
For the sake of simplicity, lets say... Goods & services were priced optimally to reduce the middle classes disposable income. The billionaire throws the poor-and-starving a bone every now and then.
Should the middle class have more disposable income? Or should charities get their bone? It's a matter of philosophy.
Being rich is being in control. You get to decide who gets your money.