My ex ahbf is what one considers 'functioning.' He works in the software field, has a great job making 75K a year, is the lead on his technical team. He once told me he feels like he's "doing something right," if he's holding a job like that. Nevermind the fact that he drinks every single night, which is the only real way he sleeps, he wakes up in the morning late for work once a week (his work currently doesn't seem to mind), feels like crap all day, and plans his evening around his alcoholic clock, all the while, wreaking havoc on relationships and people around him. He doesn't seem to have many friends, his family all lives far away (not entirely sure they know what all is up) - whether all that's the booze or him not really being the most social person, I dunno. I do know, however, it ruined us.
I hate that term, "functioning alcoholic." They should label it something like "sub-par human existence." Functioning alcoholic is something my ex ah touts. "My grandmother's 83 years old and she's an alcoholic. She's lived to be 83! I have a great job, do well for myself, I'm a functioning alcoholic!"
To that, I want to say, "Yeah, great! If only I could lose weight by stuffing cake into my face all day long! Wouldn't that be the life?" It's the same thing.
So, excellent. Since you're cool with the sub-par living style this "function" gives you, I guess you're cool with constantly making an arse out of yourself because you, yet again, said something jerky, you're cool with ducking into business alcoves to vomit randomly, or how about trying to figure out excuses to get out of plans for the evening a bit early because you just realized the convenient store that sells your wine is closing in a half hour and you have to get there beforehand? Nevermind the shame, embarrassment, and anger you feel the next day, not to mention the fact that your body feels like it's been hit by a Mack truck and you can't remember jack about anything that happened ten hours prior.
But you're functioning. So it's cool.
I just don't feel there's any "functioning" to it. Maybe on the most minimalist level, but I feel the havoc that's wreaked on people, and the fact that it limits your life in so many ways, makes it more of a wicked disability, than anything functioning.