Yes, of course it is profitable to invest in Bitcoin at the end of the year. If you could have purchased bitcoin at the starting of January 2017, you could have earned a profit giving you a higher rate on investment.
In the above graph you can see the entire journey of the Bitcoin, its ups and downs. It very well explains the price variations from the launching date of bitcoin till present situation. As fluctuations takes place, it is advised that you do a proper research before investing. So according to my opinion there is a chance that there will be rise in the prices by the end of 2019.