No, automation doesn't reduce jobs, i.e. doesn't reduce consumer spending, as consumer spending is determined by output, which automation boosts.
The savings from automation in a particular sector are spent elsewhere — wherever services are more costly (in labor). That's the dynamic behind Say's law, which shows that spending on less automatable jobs like barbers and physical therapists increases as automation reduces costs in other sectors of the economy.
I understand this is a well-developed economic theory and I am complete uninformed, but this doesn't make intuitive sense at all.
If 1 million prep cooks are replaced by robots, will food become cheap enough that those prep cooks can all get jobs as barbers, and the money people spend on food will shift to haircuts?
Will the food be so cheap that all those prep cooks can afford to learn to cut hair?
Also consider the money velocity of a human vs a robot. A human is probably paycheck to paycheck spending everything they earn. Robot earnings go back to company, which makes the stock go up, 90% of which is owned by billionaires who just keep hoarding and hoarding.
Adaptation does not require mass retraining into new professions; it happens through task simplification, AI-augmented shallow competence (less qualified people can do more advanced work), partial work, income stacking, and lower subsistence costs. As automation advances, less-automatable sectors (personal services, care, local physical work) see wage pressure rise, consistent with Say’s Law, because yes, what people save at restaurants, is spent instead at barbers, massage therapists, nail technicians, etc.
As for the gains from robotics, they go just as much to workers as to investors. Remember, investors are competing with each other, so they have to keep cutting prices. And that means workers see their wages buy more goods and services, given those goods and services cost less to buy. When wages buy more, that's effectively the opposite of inflation. In inflation-adjusted terms, that equates to a wage hike.
The savings from automation in a particular sector are spent elsewhere — wherever services are more costly (in labor). That's the dynamic behind Say's law, which shows that spending on less automatable jobs like barbers and physical therapists increases as automation reduces costs in other sectors of the economy.