One possible reason could be that he feels neglected. Maybe his family was always too busy with other things and didn't give him enough attention. This lack of attention during his formative years could have led to feelings of resentment.
It could also be due to differences in values. If Naruto had a strong sense of justice and his family had different values that clashed with his, like being more interested in power or wealth rather than helping others, it might lead to his hatred. He grew up seeing the importance of friendship and community, and if his family didn't share those ideals, it would create a rift.
One possible reason could be a misunderstanding within the family. Maybe there were secrets kept from him that made him feel betrayed. As for Konoha, perhaps he felt ostracized or not fully accepted by the village despite his efforts, which led to his hatred.
One possible reason could be feeling neglected. Maybe his family was always preoccupied with other matters, like protecting the village, and didn't give him enough attention. So he grew to resent them.
It could also be due to some external influence. Perhaps an enemy manipulated Naruto's mind in the fanfiction, making him see his family in a negative light. This enemy might have used some form of mind - control or false memories to turn Naruto against his family.
One possible reason could be a misunderstanding. Maybe his team made a decision without consulting him, which made him feel left out and thus led to hatred. For example, if they took on a mission without him, Naruto, who values being part of the team, might feel betrayed.
It could be due to a misunderstanding. Perhaps there was an incident where his sister was involved, but Naruto misinterpreted her actions as something malicious against him. Like she might have accidentally broken something precious of his and he thought it was on purpose.
Maybe in the fanfic, his sisters got some special powers or attention that Naruto felt was unfair. So he started to hate them out of envy.
One possible reason could be a divergence in values. Maybe in this fanfiction, Naruto's family holds values that are completely opposite to what Naruto believes in. For example, if his family is shown to be more focused on power and status within the Justice League world, while Naruto values friendship and helping the weak.
One possible reason could be a misunderstanding. Maybe some false information was spread within the fanfic about the Uzumaki clan that made Naruto believe they were bad. For example, if there were lies about his family's past actions that he wrongly thought were true.
It could be that the fanfic portrays Hinata as being arrogant towards Naruto's past. Naruto has had a difficult childhood and if Hinata in the fanfic mocks or belittles that, it would make Naruto hate her. For instance, if she scoffs at his time as an outcast in the village and uses it as a means to elevate herself, Naruto would surely despise her for it.
One possible reason could be that in the fanfiction's unique take, Naruto's family might have abandoned him in a cruel way. Maybe they left him alone in a dangerous situation which made him feel betrayed and thus led to his hatred.