Once upon a time, two fishermen were talking in a village near a pond. One of them had just come into the village and was cursing his misfortune. He was telling the other person about how there were no fish in his village and that was the reason for which he had come here. To this, the other guy replied saying that he could fish here as there were many ponds and fishes here. Hearing this, he became happy and both of them decided to come to the pond the next day and do some fishing.
At the same time, there were 3 fishes in the pond who overheard this conversation. Two of them started to discuss it and were thinking about what to do next. They then decided that it was best to leave this pond and go to another pond. At this time, the third fish came in between and said that it was foolish to leave just because they heard a few humans talking. To this, the other fish replied saying that he does not care about what he thinks, but it is better to be safe than sorry and so he was going to leave along with the other fishes.
So saying, the 2 fishes left the pond along with a few others. Few others stayed back with the other fish who had argued, thinking he was right. The next day, the fishermen came as planned and caught all the fish in the pond, including the fish which argued. The fish then realised that he was the foolish one and not the ones who had left.
Moral - It is better to be safe than sorry. Also, one can be confident but one must not be overconfident.