The entire value now is backed by speculation rather than "real stuff." The widely repeated "market capitalization" figure vastly overestimates the actual value given and obtainable for Bitcoins, and the price does not even closely reflect that value. The price is simply the result of what game-theorists call a "beauty-contest" game: it's based on baseless estimates of the value that others will assign to it in the future.

Alone, that's just speculation. Backed by a massive marketing push that doesn't convey the right message to the public, it's functionally indistinguishable from a pyramid scheme.