why did laurie decide not to attend the wave rally

Laurie hears a fight in the Quad. The brawl is between Brian and his rival Deutsch. Principal Owens breaks up the fight and drags Brian to his office. As he leaves, Brian yells The Wave slogans. Laurie wonders if the fight is about The Wave, but David explains to her that the boys have been rivals for a long time. David adds that Deutsch is one of the few students who has not joined The Wave. “If he was in The Wave,” David says, “he wouldn’t be trying to steal Brian’s position. That guy’s a real detriment to the team.” (86)

Laurie suddenly decides that she does not want to attend The Wave rally. David tries to convince her to go, but she insists that people are taking The Wave too seriously.