Short answer - It is considered an asset as its value is not...

Short answer - It is considered an asset as its value is not based on the economy or any other commodity. Crypto is its own entity which is by design limited in supply. The value of crypto is in its popularity.

Unlike currency which is backed by the government and its value is determined by the economy, the government controls the amount of currency in circulation.

This could change in the future depending on the uptake of crypto but for now this is how it is.