Remind me, what's wrong here?
Government backed fiat currencies tend to be inflationary. Mild inflation of around 2% is actually beneficial for the overall economy, since it encourages people to spend or invest their money rather than sitting on it. But it means that fiat currencies are a poor store of value.
Crypto-currencies tend to be deflationary. That is terrible for the overall economy, but it makes them a good store of value. Plenty of people have made a lot of money by holding onto bitcoins, but they would make a poor basis for an economy.
It doesn't make much sense to directly compare crypto-currencies to fiat currencies. They serve different purposes.