People seem to forget that the moral of "The Boy Who Cried Wolf" is that the wolf does finally come. It's not "don't panic prematurely because people will stop listening to you"; it's "don't disbelieve real hazards even after repeated false alarms".
So it's about trust and reputation. If the village elder, whom everyone trusts, cried "wolf!" the villagers would be inclined to believe him.
The moral to the listener is to not be like the boy. The moral is not, to be unlike the villagers.
TL;DR: Don't lie, or trust will be lost.