Because alcoholism is extremely trying upon those who care about you regardless and more importantly is extremely dangerous to oneself as well.
This last semester one of my roommates had a serious drinking issue. And to provide some context, we're both in a fraternity and we both live at the house. Now when I say drinking problem I don't mean drinking 3 nights a week, I mean totally drunk every single day for the span of almost the entire semester.
I noticed it was a problem after the first couple of weeks, because he never went to class and would only get out of bed to eat or get drunk. Then one night he stayed up till 4 drinking and doing coke on a week night, and cut his face open when he slipped on the stairs in the backyard. He had been drinking out of a pint glass, and when he fell the glass broke and lodged itself about and inch and a half under his right eye, so just sticking out of his cheek. It also gave him a concussion. He had to be restrained in the stretcher that the paramedics put him in because he was so damn belligerent. The following days after he got released people tried to confront him about it, telling him he might have a problem, maybe he should think about toning it down. He was incredibly agreeable and said he wouldn't do coke anymore. The amount of coke he consumed throughout the rest of the semester was... Let's say diminished, but still a very large amount of coke for one person to consume.
The next month or so was relatively uneventful, but included him drinking EVERY. SINGLE. DAY. That is until during a party he was supposed to be organizing, he got black out drunk and fell down the stairs, concussing himself again. Instead of allowing us to help him, he decided he needed to take a shower, where he proceeded to pass out several times, and each time we would have to wake him up by banging on the door. People confront him about this later, and again he seems to be incredibly agreeable, but nothing changes. They let it go because after all, it's just college.
He goes right back to drinking every single day, staying up till 3 or 4 every night, constantly waking me up and then verbally harassing me when I ask him to be quiet, being in general a total asshole to people and saying things that really REALLY crossed the line.
Then one day, after drinking all fucking day, he and his gf go up to the roof, and she falls off. Now this girl is the luckiest person in the whole goddamn world because she falls 4 stories and doesn't break a single fucking bone. She easily could have hit the concrete or impaled herself on the fence, instead she managed to hit the balcony on the 2nd floor, and rolled off off that, over the fence into the neighbors small patch of dirt in the neighbors yard. Anyways, only with that, plus the fact that housing board basically told him to either stop drinking altogether or get kicked out of the frat, only then did he stop drinking.
So maybe you should think about all the horrible shit that can and does go wrong with alcohol before you choc it up to it's just college. This last semester was the most stressful and challenging thing I've ever faced school wise, now couple that with trying to live with a man who's drowning himself in alcohol. I never want to experience that again and I don't wish that upon anyone.