Why did Wendy and Peter focus their attention on the African veldt?

For Wendy and Peter, the nursery is the center of their lives in their Happylife home. The home does everything for the family, leaving the family, especially, Mrs. Hadley, at loose ends. The Happylife nursery "parents" the children, indulging their desire to watch films of the African veldt. According to the psychologist, David McClean, who comes to evaluate the children after the parents become concerned about their obsessive interest in the veldt and its harsh "law of the jungle" ethos, including the screams of people being eaten by lions, the psychologist advises that they turn off the view screens in the nursery. The veldt dehumanizes the children and allows them to indulge the natural aggressions children feel toward their parents to an unnatural level.