You're right, of course, but it's worth noting that the current system of national fiat currencies with floating exchange rates isn't very old at all. Commodity currencies (especially metallic standards), in which the money supply is bound to a good of fixed supply, are much older and more thoroughly debugged. Bitcoin, as a virtual fixed-supply commodity, is thus built on a firm theoretical foundation.
What? Commodity currencies are not fool proof. If you find more of the commodity, your currency suffers. This happened to Spain after they started colonizing the Americas. They found lots of silver, and their economy tanked.
