I think bitcoin is an asset,because the value of bitcoin keeps increasing.If you hold bitcoin for long time you can have more profit while you sell it.
I think bitcoin is both asset and currency. If it's currency, it will the best currency with safe, fast and easy. If it's asset, it will best invest your money on this for future.
Truly speaking bitcoin has got varied features, and the best it is to use it as an investment from my opinion. Different users have difference of thinking and make use of it for different purposes. As a currency it haven't gained more importance, but the same is growing slowly. So, as an asset for large volume transactions and for market exchange purpose this has been prioritized as an asset.