Here is the psychological evidence on cosmetic surgery. If one is basically a well adjusted, healthy functioning adult who just wants some changes, then cosmetic surgery is fine. It simply is just another good "life enchancer." (Like ADDING going to the gym, getting some clothes you like, starting to attend church, deciding to rearrange your house, etc.)
However, there is amble evidence that if one is already depressed, or under any sort of prolonged mental or emotional distress, then cosmetic surgery highly increases that condition and it's symptoms. For example, it was measured a couple of decades ago that women who have cosmetic surgery have a 300% higher suicide rate than the normal female population. So, if a female (and yes, we have to focus on females...there is not enough data on males and cosmetic surgery, yet) and you feel REALLY bad over a long period of time, then thinking getting a tummy tuck, boob job, etc, will make you feel better is a myth. It will have a very short term boast, but long term the woman will be disappointed it was not a "
magic bullet" to her emotional well-being.