Yes you should not panic even if you see price going down and you should hold your coins and wait for the price to bounce back and generally people make mistake of selling at low price when they see price going down which brings only loss for them and to make profits from altcoin you surely need to have great level of patience.
Problem with a lot people is that they can't handle the stress that comes with trading. It's either them being inexperienced, or they are over-invested, or they invest with money that isn't meant to be invested. In case of the latter mentioned, people will sell as soon as they see the price go down to prevent further losses. In their stupidity, they buy back their sold coins at a premium, and repeat the whole cycle of panic selling at a loss till they end up with next to nothing. These people should stay far away from trading for their own safety.