"'I wish he was real,'" said Joe, suddenly ashamed of himself. Here he was, free in a way that his family could only dream of, and what was he doing with his frieedom? Walking around talking and making up a lot of nonsense about someone who could liberate on one and nothing but smudgy black marks on a piece of cheap paper." (Pg. 135)

This quote gives me insight on the "why?" in Joe's life.  He feels questions this within himself, wondering why he had the chance, with the family focusing it's effort on him, to leave Prague while his brother, mother, and father were left behind.  He responds by resoluting on his quest to bring them all to New York.  This drive for Joe to find some unlikely way results in the comic "The Escapist!", which metaphorically representative of Joe's quest.