It's pretty much the perfect asset, an asset allows you to generate wealth. But Bitcoin not only generates wealth it's also very liquid so that you can use it like a currency.
So it can be asset or a currency depends on how you treat bitcoin because there is no clear definition of it but as we all know this is a currency.
Well in my opinion its both it can work as an asset and as well as it works as currency because you can buy things from bitcoin and if you want to use it as an asset so you can Im also doing both when I need something so I use it to buy things and I also keep it for investment also when the price is down so then I buy and when the price go high then I sell t and get good profit.