Here's the thing. If you don't think 'Fairytale of New York' is the best Christmas song, you're wrong. I'm sorry if this is a revelation to you, that's just how it is. Maybe you don't agree. Maybe you've never really listened to the song. If the opening line "It was Christmas Eve in the drunk tank" doesn't convince you, then we're clearly operating on different wavelengths.
"I could have been someone!" is a perfect lyric, a complete encapsulation of the cry of the loser, and the response "Well so could anyone!" is equally perfect. It's just altogether great.