I just answered the question. Fiat currency is clearly useful, because it is used to pay for all the things people need. It's really pretty straightforward. Wh

I just answered the question. Fiat currency is clearly useful, because it is used to pay for all the things people need. It's really pretty straightforward. What I would say about cryptocurrency is that it is somewhat useful by this definition, but much less so. With some effort I can pay for food, but it would require a lot of effort to use it to pay for shelter, and it is not legal to use it to pay taxes. Its usefulness is a small subset of the usefulness of fiat currency.