Whether it's a failure depends upon its real value, which is next to 0. Crypto-currencies instead have a high nominal value, which is to say that they are only valued as an exchange for other currencies but otherwise have no utility. As a comparison a warehouse stocked with purchased tangible goods have a real value that can be exchanged for other goods regardless of inflation or currency activity. Crypto does not have that.

https://en.wikipedia.org/wiki/Real_versus_nominal_value_(eco...

Concretely, there are only two utilities to crypto-currency: as a speculative currency investment hoping the value of a given crypto-currency increases disproportionately to a seed currency and as a means of anonymizing currency transactions. Until crypto is used for something other than day trading or illicit purchases most people simply don't care and won't ever care as its effectively worthless in a real sense.

It's got at least one more use case: getting around inflationary problems. It's been a huge boon in Venezuela for that reason.