If you need to drink to calm your nerves before a gig, that's like needing a cup of coffee to get going in the morning. You're not actually calming down, or becoming more alert, it's just that your body (or mind) has grown depended on that in order to do what it could have done naturally on its own. If you can accomplish something that you find extremely nerve wrecking without a crutch, like alcohol, you will be off so much for the better.
As for myself, I never drink. Only got drunk once in my life, didn't like it, so I no longer did it. I also don't want to end up like my father who became an alcoholic.