1) Cosmetic surgery can improve appearance and benefit a person on a superficial level
2) Confidence can be improved by altering the attitude of the person having surgery. Some people need very little to jump start their image of themselves in a positive direction and tweaking their physical appearance can be the boost they need in order to see themselves differently. It is not just about the surgery in itself though, there is a change in attitude that helps the transformation
3) Cosmetic surgery helps people to feel more accepted by others and less inferior to some degree.