You’re a Scholar When It Comes to Your Thing
You simply can’t get enough material regarding the thing you love. You spend hours on the thing’s wiki, you read the supplementary content, and you listen to every interview with the thing’s creator. Eventually, you may even know more about the content than the person who made it. It seems strange but it does happen. Creators sometimes forget. Fanboys are then able (and likely) to explain, at length, why something is inaccurate. They may even cite their sources.
There’s nothing wrong with this side of fanboyism. In fact, it is evidence of a person’s ability to acquire an impressive amount of knowledge on a topic that has both breadth and depth. Basically, they can become an expert and being aware of that capability inspires confidence.