It is an undisputed fact that those are affected much by this sudden drop in bitcoin price are those who bought it in December last year when bitcoin was skyrocketing. I understand the emotional trauma you are going through. Nobody will be happy watching his investment losing value like that. I want to encourage you that the downfall of a man is not the end. In June 2017, nobody ever thought of bitcoin hitting $20k by December 2017 and that is the beauty of bitcoin. It takes only minutes for bitcoin price to either rise or fall. Never dump your coin out of fear. Let's keep our fingers crossed and hope for the best. If you understand that Bitcoin is a long term investment, you wouldn't panic when the price falls within some short period of time. We will all laugh soon
No, I don't buy bitcoin in December 2017 because is already expensive ($19k WOW
). But I really enjoyed this moment because of almost every altcoin price pumped (especially for coins that I hodl). I sold my coins when pumped and then it makes me rich 
I hope we can meet this moment again especially when the end of 2018, so I can sold my coins again
