There was something he said a few years ago that really struck me and revealed a lot about his attitude to booze. Paraphrasing here but it was along the lines of "when my friends get sad that means I need to share my alcohol with them so they can be happy".

He doesn't understand that alcohol is a depressant and only an extremely temporary solution to being down. That's even if it has that effect on a person because it could go the other way completely.

He thinks all of this drinking is helping him. Obviously he's a full blown addict now but he went down this road because his father didn't teach his autistic son, who was drinking too much even a decade ago, anything about substance abuse.