Incidentally, I am an economics major.
For foreign exchanges to run smoothly, some sort of counting standard has to be used. It happens to be the U.S. dollar, most of the time.
What this means is that foreign governments and individuals and corporations in foreign countries hold on to a lot of U.S. dollars. and they use them in their transactions. An important effect of this is that most dollars find themselves outside of the U.S. proper where they are being used as a sort of standard world currency.
Part of this is for good reasons: There is confidence in the U.S. dollar, otherwise, people would begin dumping them.
But is America becoming a paper tiger?
A lot of good stuff is still produced in the U.S. and some quality edge remains.
Furthermore, some countries are begining to contest a system that is partly based in international institution, which uses the American dollar. These countries are (officially): Brazil, Russia, India, China and South Africa. It's called the BRIC (South Af. Is a later addition). They are making serious plans to have their own currency system, separate from the dollar. The U.S. is not invited to BRIC meetings as it's invited to all other World Summit wathever thingy.
But you're right, the consummerist thing won't work eternally. I'm sorry, but why focus so much on homo economicus? He is still just a fiction. Are people truly insatiable or is that education? This is still an important question to ponder, in my opinion.