It's seen as being an alcoholic if you drink alone.
Sam works as a salesperson in a high stress environment and today was especially troublesome.
Sam wants to have some drinks after work to help him relax.
Sam purchases some drinks and invites his friends over to share them with.
Sam decides to pick up some alcohol and drink alone at his place.
Sam's friends think he is generous for buying them the drinks.
Sam's friends find out what he's doing and think he is becoming an alcoholic.