Most US workers were farmers a century and a half ago. In a relatively short period, 2% of Americans supply enough food to feed the entire country and export some overseas. Those who would have been farmers are working other jobs, as the market incentivises people to accept employment in sectors of the economy with more demand. When machines replace workers, they don’t all get jobs making and fixing them. Instead, they move into areas where humans have a comparative advantage over current technology. The boost in productivity that results benefits everyone.