So why do serial complainers lose credibility on and offline?
We all know these people, the kvetch or worse, the troll, the person that always brings a storm cloud whenever they discuss an issue.
Publicly everyone listens, privately they get dismissed on the back channel as a hater or worse. Eventually, people stop listening all together.
The title alone is the answer, specifically, repeat complaining.
In social communities the consistent malcontent becomes the equivalent of the boy who cried wolf. In fact, if the malcontent goes so far as to hurt others, they breed a form of reciprocity that no one really wants to see, vengeance.
A German study from the Institute for the Study of Labor shows that negative acts create a similar responsive reciprocity, a willingness to harm those who previously acted against the surveyed individual.