The people who say they need 3 cups of black coffee to start their day are just addicts with a high tolerance that experience mild withdrawal symptoms each morning.
If you feel like that, it’s your body crying for you to take a break.
If you like an occasional cup of coffee or energy drink to get through something, then that’s fine. But if you ever feel like one isn’t working like it used to, you should take a break from caffeine to reset your tolerance, not up the dosage like an addict.
“High functioning” is typically used to describe someone who is demonstrating competency at work. Academia, law, and medicine are full of these types. I’ve worked for/with a lot of them.
Home and social interactions definitely show the strain before professional life does. It’s possible for an alcoholic to function at very high levels professionally for years, but I can guarantee there are social impacts in their personal domain. Their old friendships erode, and change towards other heavy users. There are impacts in spouses and children. Their driving record may become affected, financial strains etc.
I’m confused. To me it sounds like social impacts are the results of an addiction, not part of the addiction itself. I would have thought it’s the addiction to a substance that drives changes in behaviour and results in the symptoms you describe - impacts to family, friendships, social standing. Whereas you’re saying that a body’s compulsive wanting for a specific substance is not an addiction if it doesn’t come with those social impacts. That just doesn’t sound logical to me, but hey, I’m not an expert.