Bitcoin was used as a digital currency since from the start. But this become a failure because there's a problem regarding on mass adoption and government acceptance due to its features. But still bitcoin had achieved an increasing value when some other countries are starting to use it as a mode of payment for commodities, services and some converted it to fiats. Due to its high market value, bitcoin was already considered as an investment and asset. They used as an investment because bitcoin has a huge increase of value every year. Big investors come and buy a lot of bitcoins in the market for the profit they can get from it. Bitcoin with its features made itself as an investment nowadays. And we have nothing to do when crypto community already call bitcoin as an investment.
Yeah well even though it was used quite widely as a currency at the beginning, most of it was through the silk road, as mentioned above. This unfortunately gave it a bad image and that's why there has been no mass adoption. Lawyers aren't too keen on it because of the potential darkside it has. Accountants don't see it as tangible so are a bit wary to call it an asset. Common people believe it could disappear into thin air at any given moment because of the sensationalized press coverage of a few minor hacks. Therefore the people who are using it widely are more in it for investment purposes, perhaps out of greed, perhaps out of desire to support the blockchain concept, perhaps out of a desire to stick it to the man