All of the long-dead billionaires wound up with their hordes the same way current billionaires do: exploitation. The long-dead billionaires used their immense wealth for political power, funding and writing US policy, just as today's do. They all cleared their names the same way as today's do as well: via charitable donations and foundations.
One scary difference between Mellon, Rockefeller, Ford, and Carnegie and Musk, Gates, Zuck, and Bezos is their popular perception. People (and the press) used to hate billionaires. Called them Robber Barons back then. Today's billionaires are celebrated, idolized. Short term, this means they have less rehabilitating to do in terms of their image/legacy (Musk's attempts at charity are especially bad). Long term, who knows what it what it means? Can't be good.
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