Antitrust legislation used to be very effective at dealing with this sort of stuff. These laws were designed to put an end to the gilded age (Standard Oil in particular), and accomplished what it set out to do.
Though Ronald Reagan dared asked what nobody else thought to ask, "what if monopolies ... good?", so now we're back with a new set of Morgans and Vanderbilts.
If you haven't, I'd encourage you to give "The House of Morgan" by Chernow a read.
The Morgans, Vanderbilts, etc at least built things that create value (and extracted wealth from them), things that didn't exist before in the economy.
The billionaires of today are just pure rent extraction schemes on things that already exist, make money by enshittification of what is already there. Nothing of value ever needs to be created. They use the govt to help them, after all why create anything new at all, when you can just take it?