Not necessarily sucking resources from other countries. US is a net producer/exporter for lots of stuff. Oil, natural gas, corn, soy beans are good examples of that. Even enemy states such as China needs to purchase them from the US, particularly corn and soy beans, even in these tense geopolitical times. People gotta eat.

The US may not be that great in the future, but other countries will be worse.

With the whole geopolitics and climate change, one thing good about America is we are pretty self sufficient in terms of natural resources. It's a big country with different ways of living. No adjacent enemy states is also a big plus. Worst come to the worst, the US may just go back to the old policy of neutrality and non-interventionism like it did before the second world war. Our budget may not support a global military presence anyway, but definitely enough to defend North America.

Most countries in the world depend on other countries to feed them, to provide for the energy, as well as raw material to manufacture essential goods. The "global south" is also more vulnerable to climate change. Countries like Japan and New Zealand have high standards of living, but prone to natural disasters. Europe, on the other hand, has its own cost of living and refugee crisis.

But the above is just for basic living. I think in America the odds of running out of essentials is pretty low. We will have food on the table. As a surgeon though I do recommend people to live near a metro area. Lots of rural hospitals are shutting down and they are not coming back.