I think billionaires have thought through the scenario where there are millions of starving, desperate people and law alone can’t protect them. I would imagine they prepare for it like the survivors in a zombie movie, living holed up in a compound, with similar chances of using force-based defense alone. Their defense only needs to fail once to be catastrophic (for them).

I can imagine a regressive taxed UBI that doesn’t financially impact them is a very appealing alternative to that.