First of all, most of you don't understand anything about addiction. Like Chris said, addiction doesn't require an outside chemical. Any activity that triggers dopamine in the brain (sex, gambling, gaming, eating, even exercise), can become addictive. The brain becomes used to, then dependent on, the dopamine triggered by said activity.

That doesn't mean that someone who plays games for hours at a time is necessarily addicted, even if it's every day...just as someone who exercises every day and enjoys it isn't necessarily addicted to exercise. It's when you become physically dependent on an activity to make you feel good that you're addicted.

Second, addicting to gaming has already been proven to be dangerous. Visit any MMO forum and you can plenty of anecdotal evidence. And there are plenty of documented cases of gaming addictions ruining people's lives and even leading to their deaths (i.e. Koren internet cafe binges).

Can you be addicted without ruining your life? Sure. You can be an alcoholic who doesn't need to get drunk. But I don't like my body feeling like it has to have anything that isn't a basic need (water, food, etc).

Debating about addiction is complicated because everyone thinks they know about it, but very few know the scientific literature and the debates about it. Take this article (written by a neuroscientist) about "internet addiction":

http://www.mindhacks.com/blog/2007/08/why_there_is_no_such.html

As mentioned in this same article, whether gaming is indeed considered (scientifically) as addictive is still up for debate. Also of note are the differences between "compulsion" and "addiction", and just because someone does something "too much" it doesn't characterize an addiction.