I was in rehab with a guy who drank coffee all day long. All night long. And really, lots of folks did, but he was the worst. He couldn't sleep (wonder why?) and he would get up and drink a cup at 2am. He isn't the norm but I know what you're saying. Caffeine is a mind altering substance so makes sense really. I have just never understood it because my anxiety is insane even when I'm sober so a complete impossibility for me.
That being said I do drink a big cup before workout. If I don't workout I'm an anxious mess....but it definitely helps fuel the workout. Then sometimes I have a cup after workout. If I want something more its decaf. I love the flavor but not the buzz.