Cryptocurrency as it exists today is a scam investment/pyramid scheme. Even if it was somewhat commonly used as a currency, it provides very little value above existing forms of currency for the vast majority of people. It's appeal is (theoretically) in anonymity, so it's only worth bothering with if you're trying to buy something illegal (drugs, guns, CP) and are desperate/unconnected enough to go to internet strangers for it (those internet strangers have to accept crypto in payment, too). And of course the biggest illegal market -- drugs -- is fast becoming a legal market, so who needs cryptocurrency for that anyway. But this currency discussion is all moot because price fluctuations in cryptocurrencies mean people use it as an investment vehicle, not money, and treating it as an investment undercuts whatever utility it might have as a currency.

The mistake is thinking it's something fundamentally new. It's new technology, sure, but it interacts with the market the same way a bunch of other stuff has. It's smoke and mirrors and an undeliverable product.