Consensus of valuation is the only thing that creates the societal perception value, regardless of whether that thing has real value or not. This valuation can however be either organic or manipulated. Bitcoin appears to be a new, organic movement to a valuation consensus. Fiat currencies (which were originally backed by precious metals) are now simply a manipulated valuation and therefore will likely lose this valuation after people wake up to the fact that "the emperor has no clothes."