Bitcoin created to be currency but bitcoin now is also good asset due to the increasing price of it. There is no problem whether bitcoin is considered as currency or asset, Bitcoin is a medium of exchange that better than the current currency that we use for daily life.
Like gold, bitcoin now is also a reserved asset as these two are can be mined and both are hard to mined. But nowadays, bitcoin is use more in currency for spending and paying bills and as investment that's why it's so versatile for our everyday usage and bitcoin now are catching the interest of many.