As someone who only gave up drinking every evening about 9 months ago (I now have a drink about once a week, but recognise that I still have a problem with alcohol and probably always will), I think the main reason that people drink (beyond sporadically and recreationally) is fear.
After 2 or 3 drinks, I am exactly the person I would like to be all the time - confident, gregarious, good-humoured without being leary, alert, animated and just feeling good about who I am and where I am.
Soon after, I am drunk. Slumped in a seat, focused on negative things, unwilling to participate, boring and likely to repeat anecdotes that I have told the same person several times before. But I'll keep drinking, until I am ready to sleep. The first 3 drinks are always gone in less than an hour.
The next day I will be hung-over. I won't have slept more than 4 hours, but I need to be up and doing something. I'm nauseous, paranoid and my mind will often go back to an innocuous event many years ago, where I felt I made a complete tit of myself and wince physically with deep intakes of breath.
The hang-over is the real me, it's just amplified. I'm never sick, don't get headaches, but I cannot just get myself back to sleep and let my body recover. They are horrendous days, where I feel that I am going to die or go mad.
Alcohol takes away the fear, only to return it with interest, the next day. I don't care if you are a shrinking violet, or a red-blooded alpha male. If your drinking is out of control, then fear is usually behind it.