I somewhat agree to this that they should be identified in the same categories but for me under different type since bitcoins is a currency by its nature and how it was established to assets were supposed to provide you something of value which in return will give you currency so they go hand in hand. Bitcoins can be an asset but in some different scenarios a currency because of its very high value it appears to be too much to be just spent instead investors sees it as an asset and prefer to hoard and hold it for future market purposes in case the prices go up.