[milutinovici]

No it isn't. Cryptocurrencies are not currencies at all, because they are all deflationary. More fitting name would be crypto assets.

[npoc]

There's nothing stopping an asset of increasing scarcity becoming a currency, providing the government isn't able to suppress it.

In fact, it would have an extremely strong chance of doing so due to it's better store-of-value qualities that would cause weaker currencies to flood the market and go to zero as people transferred their wealth into the harder money.