From what I see in kpop, non fans always the one who have a lot to say about the groups they don't even stan more than the fans of the group itself. Most of time, they even complaining about other groups' songs, concept, company, etc... more than they do to their faves.
In the end of the day, non fans is not a fans, they will contribute little or nothing to the group, so why the seems to care critiques more than the fans?