writing from Italy perhaps I can contribute a different point of view to your discussion. First of all, here we tend to see things through the lens of politics, and I think that this leads to the first argument against inequality: if the super-rich billionaires use their wealth to hijack the lawmaking process to further their agenda and become richer, then we have here a self-reinforcing process that can undermine our democracies. It is not paranoia, we have had billionaire Berlusconi run for office, get elected and then pass a raft of laws protecting specifically his interests (a VAT hike striking his competitor Rupert Murdoch, among dozens other) - and in the US you have the Koch brothers financing the Tea Party.
And in this game, the ones with the largest relative slice of the pie win (and this not considering the fact that it remains easier to coordinate the efforts of a few tens of super-billionaires than tens of millions of middle class citizens, the Internet notwithstanding). No pie fallacy here: as a (middle class) citizen I have to be worried that the super-rich get richer, even if in absolute term I am better off.
A concrete example: here in the EU all big Silicon Valley companies in practice pay no taxes: by using the most complicated schemes (double Dutch/Irish, anyone?) they manage to reduce their tax rate to a few %, while ordinary businesses pay something close to 40% here in Italy. You cannot imagine what level of support for far-right populist parties this is whipping up. Not good for democracy. And even worse is the erosion of the fiscal base of the state.
So Mr Graham, the problem is not that the startup founders want to get rich, the problem is that their past behavior demonstrates clearly that in order to get there they are ready to sacrifice the social compact that has kept our societies together and made them prosperous.
Their mindset has to change and no, creating foundations endowed with tens of billions of Us Dollars is no substitute to paying your fair share of taxes