If you have truly invested in the world of Crypto and occurs when prices are down then with such circumstances you should follow the market, now the price market is down and there many are sold, you as an investor must be a sell and wait until the right time to buy back or maybe buy back Bitcoin when the price goes down and this action is known as "averaging cost down".
The action for a buyback Bitcoin when the price down is a form of expectation that the price of Bitcoin will rise again in the future. For this you must really analyze carefully and need discussion from various sources so that the action is in accordance with what you want to get ...good luck