Are we so certain that no billionaire became a billionaire by advancing the public good in the first place? I am as skeptical as anyone that billionaires indivi

Are we so certain that no billionaire became a billionaire by advancing the public good in the first place? I am as skeptical as anyone that billionaires individually contribute value equivalent to their wealth, but that doesn't mean billionaires couldn't be an unavoidable side effect of a process that does contribute that value in aggregate.