You know, the same way one might forget to eat food. I keep a bottle of migraine zappers for this exact occasion when I wake up in the middle of the night with my head exploding and I’m like “oh. right. I’m dependant on a substance. nice fumble, dweeb”
I will have a slightly annoying headache if I don’t have coffee for a day or so. But I won’t drink tea for caffeine or those sugar beverages, so if I don’t have coffee I’ll accept the headaches. Because I like the taste/smell.