^ To tell you frankly, there is no one knows when is the right time to sell if you have a profit, you are good to sell but if not, keep holding.
It is possible that there is a decline of the price after a massive growth and that is right, there is no infinity growth of BTC price but we will always have a new ATH. Nevertheless, here is my point that BTC will not decline, there are too my institutional investors that keep adopting BTC and using it. It will not probably below $20k as a previous ATH, unless if these all big investors will sell their BTC at once.