There is not a single reason for any human to get access to alcohol to drink.
Edit 1:
Just to add the people who say that banning does not work is like saying banning guns does not work because people is going to find a way to get them or like saying we should not have speed limits because it does not prevent people from speeding. (Their opinions does not make sense to me)
You should focus on the why, not the what in this problem. Why do people overindulge? Try to focus on that and you reduce the excessive use of most substances.