There are many reasons. The idea of it being a day of attention-getting didn't even occur to me. I just feel like nowadays there are plenty of things to bring you down, and not that many things to celebrate. Your birthday is the one day that's literally about you, at least partly. Doing something special on your birthday harkens back to when you were a kid and it was all about you.
These days, I don't go nuts on my birthday, but there's a tradition in my family where we go out to dinner, and the birthday person chooses the place. If we can afford it, we go. That makes it special, everyone has a good time and some good food, and there's no danger of alcohol poisoning or failing a test the next day, because that's just stupid.