It's called accelerationism. It's the belief that a better society can only come about after a large disruptive event wipes out the current system. Those that survive (lots of billionaires with bunkers) will shape the new society in their eyes. It's real and it's terrifying. Like you I was mystified by the choices of the rich and powerful until I learned about this shit. Now it all makes sense...
They must have watched Fallout TV series and thought "we should do that".
But even if no civilisation ending event happens and billionaires think they could take the helm, people will rise up first. Too many hungry stomachs will not tolerate such brazen wealth inequality and power grab. The only reason that there is hardly any popular revolt yet in America is because many people are still comfortable. Wait until they aren't anymore.
They are losing those, but they haven't lost them yet. It'll take at least a few years of actually living without them for the people to wake up and revolt. The end of serfdom took from 1860's or so until 1918.
Why do you think their focus has been on robotics and AI, even as the consumer bubble has all but burst? As soon as they don't have to worry about being "got" by their own security forces, billionaires will really show how much disdain and contempt they have for the masses and any attempt to rein them in will be lost forever.
In that far flung dystopian vision, the billionaire class (in efforts to save some meaningless wealth) would hire the shittiest coders and manufacturers for their death bot army so that some 14 year old geek in Nebraska would find a way to reprogram them all to do Fortnite dances and execute their masters.