Zubon, I think that was much more true in 1950 (when I think the us. was 50% of the world economy) than it is to day, post-Cold War, when the US might be under 20% of the world economy, and where appreciation of market economics and liberal government are widely appreciated. Thankfully world economic product has heavily diversified away from the United State. With regions like the EU and East Asia, I think even a particularly disastrous US collapse wouldn't take the rest of the world down with it.