Yep, and if your intake is done by smoking, both the heat at which the smoke enters your system and all the other chemicals besides nicotine are really, really bad for your health. It's one of the very few things about the complex issue of health-related human consumption
that science has already been able to pinpoint very, very clearly.
But caffeine, even if not the most addictive substance in the world, *is* definitively addictive, both physically and psychologically. I feel it's the only substance I cannot really stop taking just by pure willpower alone (though I never did "hard" drugs, so I don't really know what I'm talking about here). There are periods when I know exactly how it feels like to be in the place of your current self, cophnia61: awake at night, unable to get myself up from bed before the afternoon no matter how hard I pull from my own bootstraps (being a freelancer doesn't help here), drinking exclusively
coffee (and/or cola) on some days... And I know the kick I feel in my brain when caffeine does its job wouldn't be necessary if I stopped drinking it for good in the long term (and maybe it can be due to the placebo effect... it feels pretty real, but I'm, literally, the last person on Earth to be able to make that call).
When I reach rock bottom, I'm able to stop drinking it for two weeks or a month by switching to other beverages like decaf, tea or, better yet, herbal "teas" not containing caffeine (reading this article
helped me in some of those occasions). If you do the transition right, that'll keep you away from the real deal for some time... but then the cycle starts again: there'll be one day when someone offers you a cup and you don't feel like saying no, or when you miss the effects and decide to go buying it... and for those times I cannot offer you any valuable advice, sorry.
Anyway, you're not alone. 頑張ってね！