I would strongly disagree. Selling your Bitcoin in a strong downtrend is the SMARTEST decision you can make. There is something called stop loss - use it or lose it!!
Buy back below 10K
How certain are you that bitcoin is going to reach 10k? The market is seemingly recovering and I don't see any clue as to why it will go down that low, of course there is a possibility that it will go down at that point but wouldn't it be better if you hodl and just buy bitcoin when it did dropped to that point and increase the amount of bitocin that you are currently hodling.