Abstinence. Personal Empowerment. Support. Inclusiveness. www.freestylerecovery.org.
Why? There are many reasons...
With alcohol, one of the most important reasons is social influence. The alcohol industry is very wealthy indeed, and drives content in television and movies as well as commercials. It becomes expected that we drink alcohol on social occasions because that's what we grow up with. It's what adults do. How many of us drank for the first time because we felt we were grown-up enough to behave like adults? This influence can't be overstated, and we have only to look at the tobacco industry since the 1960's for an example of what happens when an industry drives social influences (more people smoke), and what happens when media restrictions are put in place (fewer people smoke).
Curiosity is another reason. Humans are curious, it's part of our nature, and when we see and hear and read about drug use and the effects of drugs, particularly when it is glamorized or tied to role models, many of us will explore it ourselves. Many of us tried drugs for the first time because we were simply curious. Some of us liked the effects and used the drugs again, some of us did not like the effects and never used the drugs again.
Peer pressure is another reason. In a group of young people, often all it takes is for a few in the group to want to drink or use drugs, and many of the rest of us will follow because we don't want to feel left out or stigmatized. But this continues as we grow older. How many of us have been asked and even pressured to join our co-workers for a round of drinks at the bar after a long day? If we don't join the group, we feel left out, or we feel that others will look at us differently and negatively. Peer pressure isn't restricted to youth, it's just that our peers change as we grow older.
Sometimes we drink or use to loosen inhibitions. Drugs can be a social lubricant, no question about it, though the effects are temporary and can be embarrassing. And all it takes is one bad outcome, where we drink too much and act in ways that cause us embarrassment later, to dilute these desired effects. And, sometimes we drink or use to relieve stress. This works temporarily, but the more we drink or use as a stress reliever, the more we come to rely on it, and the more anxious we feel when we aren't drinking or using (the vicious cycle).