One possible reason could be that they are too focused on their own problems or duties. Maybe they are involved in some important shinobi business that takes up all their time and attention, causing them to overlook Naruto.
One possible reason could be jealousy. If Naruto has the rare Mokuton ability, his family might be jealous of his potential power and neglect him out of spite.
Maybe there are secrets in the family. For example, his parents might be involved in some dangerous and secretive missions that require them to keep their distance from Naruto to protect him, but Naruto misinterprets it as neglect.
At first, Naruto would likely be very confused and hurt. He has always craved family love and acceptance, so this sudden turn would be a huge blow. He might try to plead with his family, asking them to believe him and give him a chance to explain.
He might become withdrawn. Naruto, who was always so full of life and energy, could start to keep to himself more. He might stop seeking his family's approval and focus on his own path, whether it's through training or making new friends outside of the family.
It could also be due to some family curse or prophecy. In the Naruto universe, there are often strange powers and curses. Maybe there was a prophecy that said Naruto's family had to keep their distance from him to protect him from some greater evil. So, they chose to neglect him in order to keep him safe, even if it was a difficult choice.
The Kumo ninja would likely be angry at first. They'd feel that Naruto, as a symbol of hope in the shinobi world, should have noticed their problems. But some of them might also be hopeful that Naruto's arrival would finally change things for the better. As for Naruto himself, he'd probably be shocked to realize how much he'd overlooked Kumo and would feel a sense of guilt.
Kurama might become angry at first. He's a powerful being and being neglected would likely wound his pride. He could start causing some minor disruptions inside Naruto, like making it harder for Naruto to access his chakra.
He could find solace in nature. Since his family neglects him, he might spend a lot of time alone in the forest or near frozen lakes, which are in tune with his 'ice' side. There, he could discover new jutsu or abilities related to ice. This could be a way for him to gain confidence and show the village that he is strong despite his family situation.