Well ideally bitcoin is a means of investment, but if you really need the money for whatever reason, you have to sell the coins to get some sort of fiat currency back.
True, having a bitcoin is a form of investment but when time comes that we really need a cash with us, we have to sell our bitcoin. But if your are rich and doesn't need a lot of money or you have an extra cash with you, bitcoin can give us a good investment if we hold it for a long time.