It's worth the money, time, knowledge and electricity needed to mine one. It's also worth the scarcity (21 millions). Anyone can discover a new, huge amount of gold. You can't find undiscovered, new bitcoin. It costs thousands to mine one, why would it be worth less than that. It's also way more versatile. Your fiat though, is not even worth the paper it's printed on. And they print a lot of new ones, all the time. DYOR.