While that's true, if you attempted to generally reduce propensity to spend in the US economy you would see very, very bad economic effects.

It's the paradox of thrift.

To note, it has been economic policy to not have Americans save up.

Further, if you tell them it's possible they will attack you for suggesting such a thing could even be possible.

It's a perplexing attitude. OP just threw it out there as if it's an obvious fact that "people living in poverty don’t have “savings”". That is such a blatantly false statement. Poor people in developing countries have savings. I can guarantee you that even in places like North Korea, people are squirreling away the little they have, just as my grandmother did.

Poor people aren't idiots. They think about the future. They plan for the future. If they need to save, they will save.