> but at the point where there isn't enough economically useful things for everyone to do

This assumes that for example a person who has been an artist for 20 years, can easily enough switch professions to a machinist, and the only reason for them not to do it is because the economy has no need for another machinist. An insane way to think. This is not how humans work.

Let me see any HN dweller go from their cushy home office to butchering animals for meat on 12-hour shifts for example... Oh and btw, no safety net to give you food, housing and healthcare while you learn the new craft!