Jesus drank alchool (wine), and it's part of the Church ritual in Christianity. So alchool isn't a sin by default.

Getting drunk ( and doing drugs in general ), as using ressources to pursue useless pleasures and impairing your decision making, is a sin on a similar level to over-eating.

It is as a warning not to let yourself fall into depravity.

You can consider special occasions in moderation are not considered depravity, otherwise Jesus wouldn't have changed water into wine for the wedding feast at Cana.