Interesting observation after 8 months on prescription stimulants: I feel no compulsive addiction or withdrawal if I miss a day on the meds, but I regularly feel the compulsive desire for caffeine.
I drink something caffeinated less than half the days in a given week. And here I am, the day after having some coffee, CRAVING coffee like wild.
So for my body at least, caffeine is more addictive and less effective than amphetamines. I don't know how true this is for folks in general but I definitely would not have guessed this say, 5 years ago.