Well from the literature I read, it affects people differently. I drank a lot, but probably not as much as coffee drinkers.

My caffeine was mainly Mountain Dew. Couple of 20 oz bottles a day, every day for several years. Not much compared to most gamers and shit.

But for me, it was very very painful and uncomfortable to quit.

I also know someone who drank coffee every day all day, way more caffeine than I did, and she quit cold turkey. One day headache, then she was good.