I gave up caffeine for a week and it was the worst feeling ever. Felt really depressed. Wasn't sure what the issue was at the time but after a cup of tea I instantly started feeling good again. I guess I have a problem.
I used to take 200mg caffeine pills when I was younger. Didn't even give it a second thought.
Definitely addictive. I used to be on 7 mugs of coffee at work. Went cold turkey and felt like I was coming off crack. Even friends said I looked like a junky.