Most billionaires are terrified of unrestrained capitalism; they got where they were via government subsidies, regulatory lock-in, or simply measures came about at a time when they were big enough to afford regulations and their startup competitors could not.

Not that I'd completely advocate for taking the gloves off completely -- at some point, unrestrained capitalism has a tendency to devolve into absolute feudalism, unless certain non-aggression principles are adhered to. But in either case, you'd have fewer billionaires.