Bitcoin is both a very good currency and also a very good investment, so I am using bitcoin for both as a currency and as investment.
bitcoin is not too great of a currency for buying stuff at the moment because there are not enough shops at the moment that accept bitcoins as a payment method for all the goods
i usually use it as an investment because in my opinion the price should go significantly up in the near future because of the incoming halving event that will allow us to make some money from all the investments