You just said the teens will do it because they think they'd be cool to their friends. Who do you think they listen the most while they are still teens, their parents or their friends or the school?
Because in some cases teens who do all of those vices change after they get older, some friends get married and work at their father's business, some become successful working in the city. They mature eventually and stop the nonsense. Those who got deeper got worse though. I must depend and who they listen.
Kids listen to their so called
cool friends, they don't listen to their parents. In fact, kids hate to listen to their parents and many of them intentionally do opposite of what would please their parents. 14 years old kids smoke cigarettes man, they drink and take different drugs, they gamble, they do everything bad because for some strange reasons, it means that you are
cool and kids want to be cool, they want to gain attention and respect from their inner circle.
As they grow, they mature but the problem is that many of them are sometimes left with anxiety, depression, addiction and so on. Today you are a cool guy if you are on Prozac. The world has gone crazy. The maturity situation is getting worse in kids who turned adults recently.
That's what happens in most cases. I had the same idea back in the day to impress classmates thinking I would be cool in smoking cigarettes but I'm sure I snap and rebel seeing I have been to the principal's office countless times.
Growing older and coming to realize the world doesn't work the way they thought, maturity comes and discussions with friends are not about music bands anymore but how to make money or find a job. They will still come back to the old gambling ways but they will not get addicted anymore.