Usually it is a subconscious act and those doing it are unaware of the patterns they are following.
Trying to help an unwilling alcoholic will only enable them to fall further into their alcoholic abyss.
All you can do is inform them about alcoholism (why not direct them to the alcoholism guide), tell them how you feel about their drinking and then let them do what they will with the information.
Therefore from an early age they learned to take care of people. This behavior is then taken into adult life and the individual is constantly looking after addicts to 'take care of'.
Read codependency in relationships for more on this form of behavior.
We were on Sunset Boulevard amidst a crowd of jovial Alice in Wonderlands and men dressed as The Golden Girls. She “stopped by” a lot, particularly when I was not around. He flipped my plastic tray and sent the bottles flying. The next morning, I said good-bye to him for good and made a vow to myself: no more alcoholics, and certainly no more enabling such guys by carrying around a tray of their vice. A few months earlier, when we had started dating, I ignored the hints that he was an alcoholic.