It could be due to Naruto's past actions or associations. For example, if he has befriended certain outcasts or enemies of the village in the fanfiction, the village elders might think he's too unpredictable or untrustworthy to lead as Hokage. Also, his own impulsive nature at times might be a factor they consider, fearing he'll make hasty and unwise decisions for the village.
Perhaps there are false accusations against Naruto in this fanfiction. Some people in the village might spread lies about him, like that he has some secret, evil intentions. This misinformation could lead to the ban on him becoming Hokage. In the world of fanfiction, such misunderstandings can be used to create complex and interesting storylines.
He might be extremely disappointed and angry. Naruto has always dreamed of becoming Hokage, so this ban would be a huge blow to him. He could lash out at those he believes are responsible.
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 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.
A plotline could be Naruto having to deal with the remnants of old enemies. Some of Orochimaru's followers might still be causing trouble, and as Hokage, Naruto has to stop them without using excessive force. He wants to show mercy but also protect the village. Another aspect could be Naruto working on the village's infrastructure. He realizes that a strong village isn't just about having powerful shinobi but also about having a stable and prosperous community. So he starts projects like building new schools for ninja training and improving housing for the villagers.
It could be due to a great tragedy. For example, if all his friends were killed and he was filled with rage and revenge. In that state of mind, he might become a killing machine, just focused on destroying those who wronged him.
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.
In the fanfic, Naruto could hate the Hokage because of some bad experiences related to past Hokages. Perhaps he discovers some dark secrets about how the Hokage office has made decisions that he doesn't agree with. It might be something like a cover - up of certain events that Naruto believes should have been dealt with more fairly.
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.
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.
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.