Gold itself also has no intrinsic or meaningful value from a utilitarian perspective other than the one humanity collectively psychologically assesses to it on the premise that the rarer it is, the more value we all decide to asses upon it. Think about this, if you were stranded in middle of a desert, what good would 7,000 Oz of gold do for you? At that point, a bottle of water is more valuable than all that gold.
What if you were a guy stranded on an island with a couple of girls, and a lot of competing guys, surrounded by fresh water?
People are social. Shiny things have value. History has proven this.
Barring the imperfect analogy, I wholeheartedly agree with you. At least, that's what they taught us in economics, and I haven't seen concrete evidence to counter that the USD is backed by faith in the US economy.
Yet, in light of the recent debt crisis in the EU and the US, and the complexity behind the systemic risk, I question that "the economy" suffices to describe what backs it. Obviously, the economy does matter. System risk is certainly lower with a robust economy. Growth counters debt. But, if it was just the economy, then why do we need a central bank "to rescue" us? Why create more debt to resolve solvency issues in Greece? Why print money? Why have interest rates near 0%? With all of this happening, what tools are left if there is another crisis?
Then, to bring it to contrast, where does bitcoin fit in all of this? While it has its own systemic risks, is it immune from these traditional ones? In purely economic terms, it is certainly looking appealing to the saver.