I wasn't very clear in my question or its context. What I meant was, people with average ability have been able to sustain themselves for thousands of years doing subsistence tasks. Until sometime in the 19th century, most Americans dug holes in the ground and dropped seeds in them, hung around, and then dug out the result later.

In the 20th century an American of average ability could sustain themselves doing office work or industrial labor.

Beginning sometime in the late 20th century, the average American seems (to me at least) to be less and less needed in the modern American economy. Jobs are automated or off-shored.

What do we as a society do about/with those "useless" people? It's a lot of people.

Or am I too pessimistic?