As of now,there is 2 major problems with Bitcoin as an currency

1) Mining fees are too high nowdays and getting congested.In addition,the processing time of Bitcoin transaction is very slow even compared to Visa.Due to the fact that there is a limit on the number of transactions that can be completed in  a day,it can sometimes take days to even finish a simple transaction.

2) The price of Bitcoin is too voliate to be even considered as a currency. Take for example,the value of Bitcoin has experience drastic daily change of almost 5-10% in value.On the other hand,the most frequently traded forex pair USD/EUR had only a daily changeof less than 0.9% a day and bardly changed 10% over a month.The common people do not want investment denominated in a currency which value can changed by almost 50% to 90% in a month.

In short, Bitcoin is not, nor shall it be a currency.

Also Asset is something that put cash into your hands, Bitcoin is neither an asset too.