America can take of it's entire population, every single person within it's national boundaries regardless of their status and situation and make them the healthiest, happiest, most well off people on the planet ..... the country just doesn't want to
Stop thinking of America as a singular entity that makes decisions. Think of it as millions of individuals scratching and clawing to get everything they can.
I think it's more like a few hundred individuals scratching and clawing to get everything they can (and do) ..... while the rest of the millions just try to get by.