I can't tell if this is sarcasm or not, but I would go so far as to say that a vast majority of people have coffee (or another source of caffeine) in an attempt to boost their productivity.

For me, it's both. Some days, I've been up all night with a sick kid, and I need coffee to keep my head off my keyboard. But I also enjoy the flavor and drink black coffee because I think it's delicious. My comment is really about the symptoms of caffeine addiction, tolerance, and withdrawal. If I drink more than three cups a day, I get eyelid twitches. If I drink fewer than two, I get a crushing headache. If I had only one of work and kids, I'd probably drink less coffee because that way I'd be able to enjoy it more by choice and less because I have to feed my habit.