Because of our mutant powers of obsession, it’s my guess that a lot of nerds suffer from addiction. Nerds get caught up in minutiae, because there is a tremendous and fulfilling sense of control in understanding every single detail of a thing more than any other living creature. But we also tend to have a very active internal monologue (in some cases, dialog). These are some delightful ingredients—mixed with a bit of genetic predisposition—for overdoing things that make us feel good in the moment.
I think that hits a large part of the problem. But it goes further than that, especially when it comes to alcohol.
Drinking culture and gaming tie in especially well because of the large amounts of monotony. Endless fetch quests and level grinding are prevelant and gamers stick their brain with a lot of idle time. So you are given two options, find something more stimulating or take your brain down a notch or two. Gamers frequently chose the latter. A shame given the immense entertainment options at our disposal.
There is a cultural aspect as well. Geek culture looks for ways to be cool. Drinking is a cheap way to buy into a form of cool that spans genres. I can't tell you how many times I've seen gamers loudly proclaiming in guild chat or on X-Box live that they were drunk and proud of it. More often than not, these comments are met with approval. When a thirty something guildie announces they plan on getting drunk while raiding, nobody complains or wonders if there is an underlying problem. I should know, I've done it more than a few times when it would have been good to have somebody tell me to stop. While I've figured out that I was engaged in unhealthy dumbassery, I'm still holding out hope that we can convince others to keep gaming from becoming a virtual frathouse.