Well, technically, it is decent at being a currency even by your definition, just not in our society. I do think in something like a post apocalyptic world crypto would be a pretty good payment method, provided the technology worked to an extent where it would be possible to maintain.

I also refuse to believe it was invented to be speculative, I think it was basically a thought exercise to see if you could make a digital currency in a world where you can’t trust anyone.

Though the fact that right now it’s an unregulated currency that can be exchanged for regulated currency does allow for some pretty spectacular scams.