Hacker News Reader

It may, however, be a pyramid scheme, where early adopters can only profit by getting others to invest at ever-higher prices.

History will either record Bitcoin as a currency or a pyramid scheme, and anyone who says they're sure which one it'll be is either a fool or a liar.

Yes, but only in the same sense that every currency that has greater face value than the value of its physical ingredients is a pyramid scheme.

The US dollar is backed by Americans. A bit coin is backed by who?

Earthians, gaians, world citizens ;)

Including me.

Bitcoin users. Which is a larger population than that of many countries that have national currencies.

The phrase "backed by Americans" is very hand-wavy.

Humans with Internet access

... and in the same sense that most things humans do are [pyramid] schemes :-)