we convert bitcoin in dollars because you can not actually use bitcoin to buy coffee outside, we convert it to dollars or any other currency because we want to spend it to something that can not be bought through bitcoin but can be bought using real life currency.But not all the time we convert bitcoin because I personally hold it and I do not convert it yet. I am waiting for the time that bitcoin's price wil rise even higher.  Sometimes I do not convert it because I can purchase something directly using bitcoin,for example is steam games and other in game purchases.