In that argument you assume that the net effect to society of their winning billions of dollars is zero, which is obviously nonsense. For instance the net effect to society of somebody like Charles Koch is, undeniably, absurdly negative. He has (not even being hyperbolic here) the blood of thousands on his hands, with his pushing of climate change denialism. We could even argue about the net impact of Bill Gates (is Microsoft a net positive to society or negative? it's at least not obvious, and one can argue).