I answered “No”, but one might quibble about whether I actually qualify as not addicted to caffeine. (I'm operationalizing “addiction” as ‘my performances when I don't use X for a couple days are substantially worse than the baseline level before I started regularly using X in the first place, or when I stop using X for several months’. I am a bit less wakeful if I let go of caffeine for a couple days than the level I revert to when I let go of it for months, but not terribly much so and there are all sorts of confounds anyway.)