Naruto could be tired of the expectations placed on him. Everyone has always assumed he would be Hokage since he was a child. He might want to break free from those expectations and define his own path. He may feel that being Hokage is more about fulfilling others' wishes for him rather than his own true desires. So, he decides he doesn't want to be Hokage in this fanfiction.
Perhaps Naruto feels that the Hokage has been too strict or unfair in dealing with certain situations. Like if the Hokage didn't support Naruto's way of trying to bring peace and unity, which Naruto firmly believes in. This could lead to a growing resentment and eventually hatred.
One possible reason could be the pressure associated with the Hokage title. Naruto has always been in the spotlight and being Hokage comes with a huge burden of responsibility. Maybe in the fanfiction, he resents how it restricts his freedom to just be himself and have adventures like he used to.
One possible reason could be that Naruto has been mistreated by the villagers in Konoha for a long time. Despite his efforts to gain acceptance, if he's constantly faced with rejection or unfair treatment, it might lead to him not caring. For example, when he was a child, many villagers shunned him because he was the host of the Nine - Tails. This continuous negative experience could build up over time and cause him to lose his sense of loyalty to Konoha.
One possible reason could be that he has been living a life apart from his family for so long that he feels alienated. He grew up alone in Konoha, with no knowledge of his family for a large part of his life. So, when suddenly faced with this family in the fanfiction, it's hard for him to accept.
It could be that in this fanfiction, Naruto has been influenced by some false information about the Fourth Hokage. Some villains might have spread lies about the Fourth Hokage's actions, and Naruto, being young and naive in the story, believes those lies and thus starts to hate the Fourth Hokage.
One possible reason could be the overwhelming stress. Being Hokage means handling a lot of political, social and security issues in the village. Naruto might just feel that he can't take it anymore and decides to quit in the fanfiction. For example, dealing with the constant threats from other villages and internal disputes within Konoha can be mentally and physically exhausting.
One possible reason could be that their personalities don't mesh well in the context of the fanfic. Naruto might be portrayed as someone who values different qualities in a partner that Hinata doesn't possess. For example, if the fanfic focuses on Naruto's love for adventure and freedom, he may see Hinata as too reserved and home - bound, which could lead to a lack of romantic feelings.
One possible reason is the way Naruto's character arc is perceived. Some might think his transformation from an outcast to a hero was too sudden or not well - developed enough. So in the fanfic, they feel he doesn't deserve the large fan base.
In some fanfiction scenarios, Naruto might jump off the Hokage monument to follow someone or something. For example, if there is a mysterious figure or a spiritual entity that he believes he needs to follow, and the only way seems to be by jumping. It could also be a symbolic act of breaking free from the expectations that come with being associated with the Hokage monument.
One possible reason could be a misjudgment by the Hokage. Maybe they believe Naruto's power is too dangerous and uncontrollable at a certain point, so they decide to seal him away to protect the village. For example, if Naruto's Nine - Tails' power starts to go berserk and they see no other way to stop it without harming him too much.