prudent with its money
Accepting printed paper is prudent? lol
"artificial" currencies
Uuuh... and guess what "fiat money" is? It exactly means that. It's artificial currency, not real currency.
not backed by the full faith and credit of an issuing government
Mmh... and dollars are backed by? The president? It's only paper, printed at will by the central bank.
Wikimedia epic fail

+1 to accepting iranian Rials and not accepting gold and silver. Bernanke said gold is NOT money

isnt the producing cost some sort of backing, i mean you can pretty neat calculate the minimum amount of USD required to produce one bitcoin.
Nah, producing it doesn't mean it has a value. If i produce a car it has a value because it's a car, not because i worked hard to make it. If i work hard to make a broken car, it will be totally worthless, despite the producing cost

Bitcoin has a value because it has a value