If you sell bitcoin when it is dipped then it will obviously loss, it is not recommended to sell when the price falls, because that's the same you become a panic sell. Be patient to sell, because bitcoin prices still have a great chance to increase again.
Bitcoin is sought as a long term investment so one needs to be patient while investing in it. Although the price now is loitering about 8000$ but selling it now can cause you to regret in future as I believe it will soon rise up to glorious heights. So, it is the opportunity that should be abstained for now...
Bitcoin investment is quite tricky you should know what exactly the time you want to dump or to buy the important things is patients and don't be intimidated by price volatility take it as an opportunity to buy a cheaper bitcoin.