Also because I noticed only now, whether currency is paper, electronic, or any other material is not actually what tells currencies apart. But while classic legal tender is backed by the goods and services of the country that uses it (I know this part is a bit arguable but let's go with it), crypto is more or less backed by nothing but the trust that the blockchain can't be hacked. One bad hack and the value of BTC becomes 0, something very hard to do with a classic currency but catastrophic if it happens. It's also very susceptible to volatile bouts, as seen before. BTC could be a "real" currency but it would be an overall bad one that could not replace the classic currencies in it's current form. It doesn't mean it can't become one but it would have to change in ways that would take it away from the current BTC.

Take a hypothetical CMU (Close04 Monetary Unit) backed by the value of my belongings. That's a token that goes up and down in value as I buy more stuff or my house gets more expensive, or as I issue more tokens (inflation). But it's only as valuable as the trust you have in me and the laws that prop up that trust. If I sell all my stuff and disappear your token is worth nothing and there's very little you can do. There are no protections, there's no legal mechanism that prevents me from selling my stuff. For a coin to become a proper currency it needs some of those props. Unfortunately most people are internet educated in these aspects so they only understand once they get swindled. Every time a cryptocoin is abused, an exchange goes bust, you see a lot of converts and crypto regulation starts to sound better.