boozethusiast
There is a grey area between casual drinker and alcoholic, this is where the boozethusiast pulls up a barstool.
"Johnny drank a whole bottle of whisky by himself, I think he's an alcoholic!"
"No way, he biked home just fine and went to work on time. He's a boozethusiast."
"No way, he biked home just fine and went to work on time. He's a boozethusiast."