One possible reason could be that Naruto discovers some dark secrets within Konoha. Maybe he finds out that the village elders have been using him all along, not truly caring about his well - being but only his power as a Jinchuriki. This realization could be so shocking that he decides to turn against the village.
At first, Naruto would likely be extremely shocked. He has always considered Sakura a friend and teammate, so this would be a huge blow. He might question his own judgment in trusting her.
Konoha would likely see him as a major threat. They would mobilize all their resources to stop him. This could lead to epic battles between Naruto and the shinobi of Konoha. In the process, a lot of destruction could occur in and around the village.
The storyline would likely start with Naruto's disillusionment with Konoha. His actions would then shock his friends. Sasuke, for example, might initially be confused but then choose a side. There would be intense battles within the village as Naruto tries to fight against the forces that he now opposes. His former friends and comrades would be torn between loyalty to the village and their friendship with Naruto.
The scenario where Team 8 saves Team 7 instead would be quite interesting. It could introduce new conflicts and resolutions, and potentially reveal hidden strengths of Team 8 that weren't previously showcased.
It can be a very compelling twist. In fanfiction, when Naruto betrays the village, it allows for exploring different aspects of his character. Maybe he discovers some dark secrets about the village leadership that make him question his loyalty. It also creates a lot of room for complex character relationships and intense drama.
Kurenai might be a good sensei for Naruto's different team. Her expertise in genjutsu would be valuable. She could help the team develop their skills in this area, especially if the new team members have some potential in genjutsu. Kurenai is also very perceptive, which would be great for guiding Naruto and his new teammates through difficult situations.
One possible reason could be misunderstandings. Naruto is a bit of an outcast at first, and his brash personality can be misinterpreted. In fanfiction, the team may misjudge his actions as being self - centered when in fact he's just trying to prove himself. This could lead to them hating him.
Sasuke might become more withdrawn. He was always in a sort of rivalry with Naruto, and without Naruto there, he could lose some of his motivation to get stronger. Sakura would be devastated. She cared about Naruto, and his leaving would make her question what went wrong. Kakashi would also feel a sense of failure as a teacher.