I am putting this idea out there as a broad generalization, but I think overall it is correct: the internet is now addictive. Not for everyone for sure, but for enough people I think it is or is quickly becoming a problem.
The rise of Facebook combined with Twitter, internet games, and smartphones adds up and creates an intoxicating environment. I am starting to see some new surveys that show how often people are on the internet. The totals keep getting bigger by the year.
It'll probably take a few years or so before legitimate internet addiction studies are done. However, I think common sense shows that it is becoming a significant social problem. One issue is that all the financial incentives are to keep people online, not off. If you can get people online, then there's money to be made. If someone says, "the internet is addictive, people need to log off", how can they make money off that message? That's a tough sell, and so the message wil get drowned out by the internet profiteers.
Just over the last few weeks, I've had a major shift in attitude about my screen time. It felt like something clicked mentally, and I realized that I needed to diversify my leisure time more into other activities. (Hence, the last post on the Paleo lifestyle).