aneka is correct. These are the major reasons people begin drinking; and, the reasons they become problem drinkers. However, with all the efforts that aneka outlines, they can stop drinking; and, some can even go back to social drinking. But, there are some of us for whom the addiction goes even deeper.
It has been discovered medically that alcoholism is a disease - an alcoholic's body does not handle alcohol in the same manner that non-drinkers or social drinkers do. Alcoholics can never be cured - no matter how long it has been since our last drink, once we drink again we will be back where we were (or worse) within 6 months.
There is only way to stop the progression of this disease; and, that is to stop drinking entirely.