It's not fiat because you can't create Bitcoins from nothing. If you can then create one. I dare you to create a single Bitcoin.
There is also a voting mechanism that can change the Bitcoin protocol, the NSA for one probably has enough computing power and bandwidth to flat out 'take over' the network and give themselves arbitrary bitcoin amounts.
PS: Voting is a basic problem with all network based protocols. If enough machines say this is what happened then that's what happened.