What does alcohol consumption have to do with technology? Most people here are looking to read about tech, not yet another subjective study about the effects of alcohol.
Ah you mean why is it on HN, not why was the study performed. That's fair.
HN is wider than just technical things of course, and often includes major breaking news as well as some things of general interest. Given how common alcohol consumption is, that's probably how it ends up on the front page.