The ones I have come across have generally stated that they will engage in private charity if the government stops taxing them. It holds all the value of an election promise. But if you're not on the poverty line and you're not already giving to charity, you won't magically become charitable with the application of more money. It's just not how people work.

And certainly, if you're not giving to charity now out of some sense of 'cave deservedness' like clarky07 above, then nothing will make you give continuously to people in lifelong need of financial support.