I've seen first hand what too much alcohol can do to a person. Too much is a very subjective, and unfortunately, unknown quantity - until it's too late. Alcohol dulls the senses, fogs the brain, blurs the eyes, kills brain cells. In retrospect I can't imagine why anyone would purposely do that to themselves.
I find it very strange that if I'm offered a drink and decline the comments range from 'What's wrong with you?' to 'Oh, another goody-two-shoes>?'. If I say no thanks, I'm a recovering alcoholic the comments tend to be totally accepting.