>> The whole Australian or U.S. or Japanese economy backs their currency.
Exactly!! With more and more businesses accepting Bitcoin the same principal applies to Bitcoin. BUT it will be a global huge economy.
Bitcoin is a crazy wild idea. But it works. It has been working for 4 years and is only getting stronger. The thing is the more you think about it and the more you compare it with fiat, the more you like it! Give it a go. Bitcoins are not bombs. Come on! If you have an iPhone install BlockChain app, or if you have an android phone install bitcoin wallet app. Then post your address and I will send you $2 worth of bitcoin for free. No string attached. Without Bitcoin how on earth would someone give you money without even knowing your name?