One possible reason could be that he gets tired of the constant fighting and bloodshed. He might have seen too many friends get hurt or die, and it just becomes too much for him to bear. Another reason could be that he discovers a new purpose in life outside of being a ninja, like focusing on family or helping the village in a non - combat way.
One reason could be the excessive toll on his personal life. He might have realized that being a shinobi means constantly sacrificing his time with family and friends. For example, he missed out on important moments in his son's life. Another reason could be disillusionment with the shinobi system. He may have seen the corruption or the never - ending cycle of violence within it and decided he no longer wanted to be part of it.
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.
It could also be due to personal growth. Naruto might have outgrown the ideals and limitations of being a Konoha ninja. He may have developed his own set of values that no longer align with the village's ninja system. For example, he could have found that the constant focus on missions and loyalty to the village overshadowed the importance of individual freedom and justice on a broader scale.
Maybe he realizes that the shinobi world is too corrupt. There could be political intrigue and power struggles that go against his ideals. He has always fought for peace and unity, but if he sees that the system is beyond repair, he might choose to quit. Also, he could have a family situation that requires him to step away from the shinobi life. For instance, if he has a child with special needs that demands his full attention.
It could be that Naruto has other creative or intellectual interests. For example, he might be more interested in art or learning about the history of the ninja villages rather than participating in ninja battles. He could find the rigid ninja training and the constant competition unappealing. Also, perhaps he has a different sense of purpose, like wanting to focus on building peace in a non - combat way, which doesn't require being a ninja in the traditional sense.
In some cases, the fanfiction might be a crossover with another universe where the idea of a ninja doesn't fit. So, to make Naruto fit into this new universe, the writer has to take away his ninja identity. This allows for new and interesting interactions between Naruto and characters from the other universe.
One reason could be that he gets tired of the constant danger and the toll it takes on his personal life. He might have lost too many loved ones due to his superhero identity, and he just can't bear the pain anymore.
It might be due to a lack of inspiration. Writing fanfiction requires continuous creativity, and if they ran out of new ideas related to Naruto and the ninja world, they could decide to quit. For example, they might have explored all the character arcs and plotlines they could think of within that context.
One possible reason could be that he experiences a great personal loss. Maybe he loses someone very dear to him during a mission, like his best friend or a respected mentor. This loss makes him question the whole ninja life and all the violence and danger it entails, leading him to give it up.
One possible reason could be that he experiences a great loss, like the death of a dear friend. This might shatter his confidence and make him lose his passion for being a ninja.