I think bitcoin is an asset, because we can not use it the way we use fiat currency.
It's mostly used for trading. That's why we consider it an asset that makes Bitcoin still very attractive, because when the Bitcoin price goes up a lot, the people who see Bitcoin as an asset are encouraged to sell,
I think bitcoin have them both as its characteristics. It could be a currency because technically it's a digital or cryptocurrency. On the other hand it's asset because of the owning and holding technique that we're doing. This is a wealth found on internet and investing in it makes it as an asset.