It was more true at one time. Certainly, post-WWII as our country wasn't bombed to bits, so our economic engine was primed and ready to go. But globalization has leveled the playing field, the financial crisis shook things up, and all of the last 4 years is going to reduce the rest of the world's dependency on the US. Someday, China will have a larger economy than the US, and in the far, far future India probably will as well, with Brazil running along side the US. Population and resources matters, but they have been shooting themselves in the foot for generations (lets add in Russia too) because shockingly, progressive human rights tracks with economic prosperity.
And Mom, I am going to my room now. Sit on my hands. No computer.