Why were native american boys referred to as “good for nothing” when they returned home from attending a white college?

Native Americans, as much as America had alliances with certain tribes, were still seen as a potential threat to their lands. With this, tribes often thought of them as "dumb" and "unintelligent". So, naturally, when Native American boys were admitted into white colleges, they came home "unintelligent" and seen as "disgraces" because of their admission. They thought that if you learn the white man's way, you would be submitted to be swarmed with illogical information.