The ingredients are listed as:
Carbonated water, citric acid, flavourings (including caffeine and quinine), sweeteners (acesulfame K, aspartame), preservative (E211), colours (E110, E124), ammonium ferric citrate (0.002%)
There's nothing in there which I'd recognise as addictive (other than caffeine, of course). Equally, there's nothing that's obviously 'bad for you'.
Your craving for the stuff could either be entirely psychological or it could be that a genuine medical condition (such as type 2 diabetes) is making you thirsty and your brain is simply selecting something which it associates with quenching thirst.
Chris