Answer:
Because the predator species being in that ecosystem would harm the other possible species in the area. This would cause the diversity of animals to decrease, and also make the predator species into a larger group as they grow, and develop a taste for those animals that they feed on.
Because the number of predators go up, the amount of other species in that area will go down. After there is no prey left for the predators, the predators will also soon die out due to the lack of food in that area.
