Coders in general are susceptible to alcohol for these kinds of reasons. Add in flexi hours (hey it doesn't matter what time I show up as long as I ship code, right?), and it's practically the ideal job for a functioning alcoholic.
I've seen dozens of fellow programmers slip down the slope. It's particularly bad in the financial sector in London, where "trader culture" of hard drinking, drugs and women is seen as acceptable. Usually it's well concealed until early to mid-thirties. Often their situation rapidly degenerates after a relationship breakup or family bereavement. What's fun and social when you're with your friends in your 20s isn't so much when you're 35 and lonely.
It's striking how casual and uninformed the general attitude to this drug is in our industry, e.g. http://zachholman.com/posts/how-github-works-creativity/