"People change people"
Teenagers are always complaining about themselves. They are used to depend on society's opinion. Why do they think like that and listen to other people? Because their own rate is not based on self-esteem, but on thoughts of society. If society is killing you mentally - you'll be killed. But also if your environment helps you, likes you, etc., you'll be more happy and confident. That's okay, because we listen to other people. Because people change people.