long term investment is more profitable that short time investment, but you need to invest a good amount for long term investment, as you have to wait for a long time and to give some good time for trading therefore you need to put some good amount for long term investment so as to get some good profit.
I think long term investment in bitcoin is profitable as you observed bitcoin prices is higher compard to the vety beginning continue to rise. Though in between there up and down but in overall it is uptrend.