There is no natural law which ensures that everyone has earnings potential greater than cost of living.

Indeed not, but that correct idea often leads people to the incorrect idea that robotics-induced disemployment, and subsequent impoverishment, are technological inevitabilities. Whether people everybody is going to have enough income to eat depends on how the (increased) wealth of such a society is distributed .. basically to get to the worst-case scenario, you need a sharp decline of interest in wealth redistribution, even compared to US norms. It's a matter of public policy, not technological inevitability. So it's not really the robots taking over people should be afraid of, it's the libertarians taking over.

New tech isn't making food or housing cheaper fast enough,

I am not sure what that is supposed to mean. There is enough food and living space to go round, globally, but it is not going to everyone who needs its, which is, again, re/distribution problem