Another reason could be related to the shinobi system. If Naruto witnessed the dark side of the shinobi world where humans were using and sacrificing each other for power, he could develop a hatred towards them. He might have felt that humans were inherently selfish and cruel in this system.
Perhaps he had some really bad experiences with humans in general. Like if he was constantly persecuted or discriminated against just because he was different. He might have seen so much cruelty from humans that he grew to hate them all.
One possible reason could be betrayal. If Naruto was constantly let down or betrayed by those he trusted among humans, it could lead to his hatred. For example, if his friends turned on him because of his jinchuriki status.