So It Goes?

At the beginning of the book, I thought that the "So it goes" was something that was always said after somebody died. I came across this line many times throughout the previous chapters, and had always thought of a way of remembering the person that died. This is what I believed until I read a weird line. That is when I first realized that I was reading the book completely wrong. Many parts of the book are ironic, but I had been reading it as if it were a history book. I felt silly, and then started to look for parts that were not supposed to be serious. "So Billy uncorked it with his thumbs. It didn't make a pop. The champagne was dead. So It goes." (Slaughterhouse-Five, PDF File) I was shocked to read this because I couldn't believe how wrong I had been reading this. Vonnegut in a way is making fun of himself when he says "So it goes". The champagne is not a person, but since he has said that line so many times, he laughs at himself by acting as if the champagne was a person because it didn't pop. To be sincere, now when I read "So it goes" I just look at it and laugh. How could I have taken such a book so seriously?