Hey there!
A question of panic selling was already discussed on this forum a billion times. But whats bad here? If you are sure that the price will grow back then you can just buy some BTC in better rates. The more dangerous will be the situation when someone is buying BTC while being afraid of loosing some profits despite the fact that pump has already happened (I'm calling it a panic buying). Thats seems like a straight way to lose money and make a bubble.
Take note that investing is risky, that's why people advice to invest at your own risk. There's nothing bad about investing anytime, it depends on your aim or purpose for investing. If you are investing and holding for a long time, price changes shouldn't be a big issue because if you trust bitcoin, you are aware that bitcoin price will grow in the long run.