well, I am ADHD, so my dopamine and noradrenaline levels are low to begin with.
this is worth reading:
https://en.wikipedia.org/wiki/Low_arousal_theory
if you liken dopamine in ADHD to testosterone in men who are low testosterone, things make a lot more sense. and I *am* high testosterone, which is known to deplete dopamine faster. e.g.
https://www.reddit.com/r/DrugNerds/c..._depletion_by/
in fact, if you look at my old post history on this website like 10 years ago -- that was all ADHD shit. I used to start arguments because that was what woke me up + engaged me. with stimulants, I do this a *lot* less. (make no mistake: it's still fun, but I don't get nearly as much out of it.)
so really, caffeine is too weak of a stimulant for me. stimulants like amphetamine (adderall) will make me not only functional and in a far better mood, but allow me to perform at 100%. to really drive this point home, my IQ increased by something like 10 points after a year or so of using stimulants. my ability to produce, evaluate and retain information was augmented massively. it was like someone turned on a power supply to my brain when I was previously running on low-battery mode or something.
I will say that methylphenidate (ritalin) doesn't do much for me though, so dopamine isn't the whole picture.
otherwise, I am lower-than-average dopamine and will be the grumpiest asshole you don't want to interact with. this has been more or less the case since I was a teenager.
so to directly answer your question, I am not 'addicted' to caffeine or stimulants so much as if I didn't take them, I'd function at 60%, and taking them helps me function at 100%.