congratulations for those of you who bought bticoin when the price was under $5.5k because at the moment the price of bitcoin has gone up in price and can reach prices of more than $9k and has the potential to rise to more than $10k. so I suggest you keep waiting until prices can return to the end of 2017, the price can reach $20k.
they gain almost 100% from their investment now.and its still have possibility to continue on its value.holding till 2021 will be good , wait halving event and sell if after that.they no need to worry if btc price goes down cause they bought it on lowest price.