This is a jukugo word that uses the on'yomi readings of the kanji. Well, at least most of it does. To remember the reading for 哀 imagine some pathetic person who lost their home. They may be pitiful but at some point after losing their home they decided that the hood of your car would make a fine place to live. You can't help but ask them, "Why (わい) my car?" There are so many other cars this pathetic person could be camping out on, but they chose yours.
I think it’s a little pathetic to be a social drinker.