I think some people don't want to be THAT PERSON who doesn't drink, because there's an assumption that non-drinkers are boring and no fun to be around.
I think the opposite is true - drunk people are awfully boring and tedious to be around, especially when they start repeating themselves every five minutes.
I've had the best times of my life in the past three and a half years since I've stopped drinking. This isn't directly BECAUSE I've stopped drinking, but it's been a part of it.
Imagine there was a button which, when pressed, would make you wake up the next morning a load of money short, with massive gaps in your memory and no idea how big a tit you made of yourself, and the fear and anxiety that goes with it. Why would anyone press that button?
To anyone reading this - if alcohol is having a negative impact on your life, your mental health, or anything at all, then don't be afraid to say cheerio to it. Alcohol is no one's friend.
EDITED TO ADD: I'm actually 30 today - it's good to be able to enjoy such days without the carnage.