Internet addiction?

I just listened to a show on public radio where a psychiatrist argued that there should be an entry in the DSM, the official bible of psychological diagnoses, for internet addiction. Apparently, the criteria is not the amount of time one spends online, but the effect this time has on one's actual (ie: not virtual) life, relationships, job, etc. That sounds sensible, but it raises a rather interesting question of what constitutes a disorder in itself and what is merely a symptom of something else.
I suppose one could even argue that those who spend lots of precious time writing (and reading) blog entries suffer from some sort of pathological condition. However, I suspect as with most things, it has everything to do with one's attitude toward the activity and not so much with the activity itself.
For some people playing the lottery occasionally is a minor amusement that they could dispense with easily. For others, it is a vital part of their every day lives. They might feel that should they skip a day or not buy many dollars worth of tickets every day, they would cause their own financial ruin, when they are actually probably facilitating that ruin by playing those tickets. In this case, as in other similar ones, it's not the lottery tickets but the attitude that makes all the difference, and minus lottery tickets, they might take this attitude toward anything at all, even something people might regard in a positive way in most instances.
So perhaps the internet is not the problem? Yet I don't buy the maxim that "Guns don't kill people; people kill people." Isn't this the same argument?
Ah consistency! It makes my head hurt!