Research shows no long term effects after age 6, positive or negative, of sleep training, so the research doesn't support your hypothesis.
Research shows many positive effects before age 6, both for the child and the family.
Research shows many positive effects before age 6, both for the child and the family.
The only valid research says that they stop waking up their parents. This is probably due to learned helplessness, which leads us to the hypothesis in my first comment.