If they’re not trading with everyone else they’re not rich. Being rich /is/ the ability to trade a lot.
The idea that rich people will all leave and start a different rich-people-only economy that somehow takes all the economic activity with it isn’t how it really works, it’s the plot of Atlas Shrugged.
Why do you need consumers when you have machines making most of what you want? Then you just need to be able to trade things with other people who have different machines and resources from yourself to get the bits you can't have made by your machines.
Where do the inputs for the machines come from? ex: having a machine that generates CPUs out of sand and works for free would mean cheaper CPUs, but it would also mean a lot more employment in the sand industry, and there might not be a machine for creating sand.
Nope. He is saying power concentration will increase further. This is also Yuval Noah Harari's thesis. You can read about how that will get achieved here.
The idea that rich people will all leave and start a different rich-people-only economy that somehow takes all the economic activity with it isn’t how it really works, it’s the plot of Atlas Shrugged.