In Galapagos, humanity has undergone an utter crash of the fiat economic system. Nations haven't become penniless, but rather their pennies mean absolutely nothing. Emphasis has been placed back on material goods, and currencies around the world have been rendered useless. In the fictional 1986 world Vonnegut has established, the characters are in the midst of this fiscal deterioration of society as they know it.
Having done some research on Vonnegut and Galapagos, I learned that it is very likely Vonnegut drew inspiration from the Latin American Debt Crisis of the 1980s. In the 1970s, there was a big push for lesser developed countries to industrialize, and many Latin American and African countries borrowed money in order to do so. While growth was measurable and observable for a short time, the slow world economy of the mid 70s combined with increasing oil prices and raising interest rates in the West caused progression in the less developed world to simmer down. Countries such as Brazil, Argentina, and Mexico struggled to repay debts, and the value of their respective currencies depleted drastically.
When people are scared or insecure, they look for tangible things to cling to (although one could make a solid argument for the opposite view). In poor economic periods in the United States, the price of gold increases. There is a certain amount of risk in the fiat system, for if enough fear is infused into a culture or a nation or the whole human race, the entire system can collapse, as Vonnegut shows us in this work. I'm positive Vonnegut used this premise to make the reader reflect on his or her own faith in the invisible realm in which we deal with every day.
For more info about the Debt Crisis: www.economicshelp.org/blog/glossary/debt-crisis-latin-america/