Of course, i should narrow my statement down a bit. If a fandom is dedicated to the fiction they like and enjoy that fiction, but people say to the person, "Hey that fandom is toxic, why are you in it?" And that will make the person think that their beloved fandom is toxic and will drive that person to distance themself from the fandom.
Yet, the person who said that the fandom is toxic doesn't get that if someone from the fandom is really toxic, it doesn't make the entirely of the fanbase toxic. It is just that person who does.