I doubt that it is coffee to blame.
I believe that many people have some addiction to coffee. I, for one, cannot wake up without a cup of coffee. If I don't drink coffee I feel very sleepy and inactive which is awful because I don't care about anything else but return to bed and keep on sleeping while I am in such condition. Many people have different ways to raise their activity, I actually have several ways. Coffee is one of the stimulus which lifts my spirits. One more method is to do some physical exercises like push ups or crunches or something else. It does good not only to your body but to your mental side as well because it is essential to switch your attention from one activity to another from time to time.
Maybe some people feel how coffee affects their trading and attention but I got used to coffee, so I don't think that it has any impact on me.