The title you indicated and the description that was said for fiat contradicts.
We would love to call this a misleading title. 
Actually every currency in our days dont have real value. It all based by trust and reputation
And that says for the fiat because we trust the government and the reputation they have can't be stained in terms of monetary system. They declare whichever have the value and how much it will be. But bitcoin is a different thing from the traditional cash that we have which the value was made by them. Upgrade00's explanation said it clear how's bitcoin value/cost is made.