I do not have confidence in the national currency, because it is easy to make, especially for my country. $ 1 = 23,000 VND. The currency depreciates gradually, the state prints continuously.
My national currency is not reliable as well. The exchange rate between it and the US dollars is outrageous and that makes the price of things go higher and higher. The same cannot be said of Bitcoins. I'd rather use Bitcoins than my national currency.