This is true, but gold at least has a several-thousand-year history of use as a currency, and as a stable source of value. The US dollar that we use today has

This is true, but gold at least has a several-thousand-year history of use as a currency, and as a stable source of value. The US dollar that we use today has a history going back to exactly 1971 and the end of Bretton Woods. I think people get a little too worked up over the evils of "fiat currencies," but they do have a point that from a historical perspective they are basically an experiment. It's entirely possible that people may look back from a few centuries hence and look at floating national currencies (which are essentially backed only by the backing government's power to tax a particular economy) and think "what a really terrible idea." The very power that a fiat currency gives a government over its money supply might turn out to be more temptation than even the most honest government can withstand in the long run. We don't know, because there just hasn't been enough time to tell. There's two orders of magnitude difference between the amount of time gold has been in use and the amount of time the current un-pegged dollar has been around. While it's true they're both given value by what other people will trade for them, it's a bit disingenuous to say they're the same.