Well, perhaps in these fanfics, Harry has seen too much death and destruction in the wizarding world. He might avoid it to protect his mental health. Also, it could be that he's trying to break free from the expectations placed on him in the wizarding world. He wants to define himself outside of the hero role he's been given.
In some fanfics, Harry could avoid the wizarding world because he's disappointed with how things are there. There could be corruption or inefficiencies that he doesn't want to be a part of. He may also be on a personal journey of self - discovery that he feels can't be achieved within the confines of the wizarding world. He might be looking for a place where he can be just Harry, not the Boy Who Lived.
One possible reason could be that in some fanfics, the author wants to explore a different side of Harry. Maybe he's tired of the constant chaos and danger in the wizarding world. Another reason might be to show his independence from the typical wizarding narrative. He could be seeking a more normal life away from all the magic and politics.
One possible reason could be the trauma he has faced. Harry has endured a great deal of pain, from the loss of his parents to the constant battles and threats in the wizarding world. He might want to escape all that and find peace away from it.
One possible reason could be that he's tired of the constant danger and politics in the wizarding world. After all he's been through so much. He might just want a normal, quiet life away from magic.
The plot could start with Harry making a firm decision to leave. He might go into hiding in the Muggle world, changing his appearance and identity. Then, the wizarding world would gradually realize his absence and start to search for him, which could lead to a cat - and - mouse chase.
One possible reason could be extreme anger. If something really bad happened to his loved ones, like if Voldemort came back in a different way and killed all his friends and family this time, Harry might be driven to the edge and decide to destroy the wizarding world that couldn't protect them.
Perhaps he leaves in search of a more peaceful life. The wizarding world, despite its magic, has been filled with turmoil for him. He could be seeking a place where he can simply be Harry, not 'The Boy Who Lived' or the hero who defeated Voldemort. He may also be on a quest to discover more about his family's past in the Muggle world, something that has been somewhat overlooked in his life in the wizarding world.
One reason could be that he's tired of the constant danger and battles. After all he's been through, he might just want a normal, peaceful life away from magic. Maybe he wants to start a family in the Muggle world where his kids can grow up without the threat of dark wizards.
It could be about Harry Potter achieving ultimate power and ruling the wizarding world. Maybe he overcomes new and even more dangerous dark forces and in the process, he becomes the king. He could make new laws and bring about great changes to Hogwarts and the entire wizarding community.
In certain fanfiction scenarios, Harry could leave the wizarding world to explore other magical realms or non - magical places. He may feel that his growth and understanding of magic and life are restricted within the wizarding world he knows. Maybe he meets a group of people from outside the wizarding world who offer him a new perspective and a chance at a different kind of life.
Perhaps he feels betrayed by the wizarding world. Maybe some of his friends turned on him or the institutions he trusted failed him. For example, if the Ministry of Magic wrongly accused him again, it could push him to abandon it all. He may also be haunted by the many deaths he witnessed and feels that leaving is the only way to escape the painful memories.
Perhaps he feels disillusioned with the wizarding society. There could be issues like corruption or inequality that he can't bear anymore, so he decides to leave. For example, if the Ministry of Magic starts to misuse its power, Harry might not want to be part of such a world.