The boy who cried wolf

I am sure all of you have read or heard the story of the boy who cried wolf because he was bored. When the real wolf came, he cried wolf again but nobody helped him since he was a liar. The point that I don't understand is the moral of the story. When villagers didn't help the boy, their sheep were scattered and slaughtered. So the moral of the story should be if somebody is lying, listen to him/her every single time or you might be the looser at the end of the day.