I guess the idea is that the people left working will be made so productive and wealthy thanks to the miracle of AI that they can more than make up the difference with extravagant consumption.
The comment wasn’t on the trend or where things are going and the historical progress the country has made. The comment was on the current state of the economy. The fact that wealth concentration creates its own unique challenges. If as many people were unemployed and in poverty (or in the low income bracket) in the US or any other developed nation, the living conditions would have been drastically deteriorated. The consumer market would have shrunk to the point where most people couldn’t afford to buy chips and soda.