Americans do not realise that the world economy entails more than iPhones and cars - much of it consists of money. Lots and lots of money. And guess what the EU (and the rest of Europe) has a lot of?
Imagine the shockwaves once the Norwegian pension fund starts to treat the US as the pariah that it is. That's the largest wealth fund in the world, over $1.7 trillion, owning 1.5% of all publicly listed shares in the world (!).
Americans have no idea what's about to hit them.