Picked the wrong friends.
Sorry...I've lost too many friends to alcoholism, they all started drinking as kids and by the time their brains had a few cells - they were already being destroyed, because they were hooked. By the time they were twenty they couldn't last five minutes without a smoke in one hand and a drink in the other. It became a convenient and addictive escape mechanism.
Hmm, nearly all the friends I made in high school that experimented with drugs and alcohol figured out moderation in their adult lives and went on to real success. Maybe it has more to do with the group of people you consider friends.