One common reason is the feeling of inadequacy. Naruto often aims high and wants to be the best, so if he falls short in a fanfic's story, he may start to hate himself. For example, if he fails to master a new jutsu quickly enough or loses a fight he was expected to win.
Sometimes, in fanfiction, the author might create a situation where Naruto is constantly compared to others unfavorably. If he's always made to feel like he's not as good as someone else, whether it's in terms of power, intelligence, or popularity, this could chip away at his self - confidence and eventually lead to self - hatred.
One reason could be that some fans are very purist about the original Naruto story. They might feel that fanfiction often distorts the characters or the plot in ways that go against the essence of what Naruto is all about. For example, changing a character's personality completely to fit a romantic or dark and edgy narrative that doesn't align with the source material.
Perhaps in the fanfiction, Naruto discovers some dark secrets about his past, like his family's involvement in something he considers immoral. This new knowledge could make him question his own identity and lead to self - hatred. He might feel that he's a product of something bad and that he can't escape this 'taint' no matter how hard he tries.
One possible reason could be the burden of his past. Naruto has faced a lot of hardships and the memories might be overwhelming him, making him want to be alone. For example, the loss of his master Jiraiya might have left a deep scar, and he might feel that isolating himself is the only way to deal with that pain.
Maybe he feels a sense of guilt. For example, if something bad happened in the village that he blames himself for, even if it wasn't really his fault. He could exile himself as a form of self - punishment. He has always been very hard on himself when it comes to the well - being of the village and his friends.
One reason could be their distrust. Since Naruto was a jinchuriki, the civilian council might have been overly cautious or even discriminatory towards him. This could lead to Naruto hating them for not seeing him as an individual but as a potential threat.
The different power scales. Naruto has his own progression of power through training and ninja ranks. Superman's power is on a completely different level like being able to move planets. In fanfiction, it might be hard to balance their powers in a way that makes sense to Naruto fans, so Naruto might seem to 'hate' it.
Perhaps in fanfiction, Boruto is associated with a group or ideology that Naruto opposes. This could cause Naruto to view Boruto unfavorably. Also, if there are false rumors or misinformation spread in the fanfiction world about Boruto, Naruto might believe them and start to hate Boruto until the truth is revealed. And sometimes, it's just a way for the writer to make an interesting and unexpected plot twist.
Maybe Naruto hates it because the two universes have very different power systems and cultures. Naruto's world is about ninjas, chakra, and village politics, while Avatar has bending elements and a different kind of spiritual connection. The fanfiction might misinterpret or blend these in a way that doesn't sit well with Naruto fans who are purists.
One possible reason could be a misunderstanding. Maybe some false information was spread about his mother, making Naruto believe she had abandoned him. Another reason could be related to the secrecy around his mother. If he grew up feeling alone and not knowing about her, he might develop resentment.
A possible reason could be jealousy. If Naruto had a sibling who was always favored by their parents, he might grow to hate his family. He would feel like he was always in the shadow of his sibling and that his family didn't care about him as much.