"unboundedness of the greed of a few"
Lots of people claim "greed", but the stereotypical Tech billionaire doesn't simply roll around in gold like Scrooge McDuck, doing nothing and demanding more. They invest and reinvest it into new enterprises.
Of all the ways of dealing with massive wealth, this is probably the second least disruptive one. (The first one would be just giving it to honorable causes.)
They claim greed because they always choose the path that makes them more money even if it has clear, evidence-based proof of societal harm.
Ya know, just like the Sacklers and pushing oxycontin.