Final answer:
The author uses the provided passage to illustrate the vibrant atmosphere and fan engagement at a Billie Eilish concert, highlighting unity and participation.
Step-by-step explanation:
The passage "I'm in love with my future," Billie Eilish sang. Over 17,000 people were in the crowd. Excited fans raised their voices. They joined in, never missing a beat," is primarily used by the author to convey the atmosphere of the concert and the engagement of the fans with the performance. The detailed description of the crowd's reaction creates a vivid image of the event, emphasizing the strong connection between Billie Eilish and her fans, as well as the shared experience of the music bringing everyone together. This captures a moment of unity and participation, where the fans are not merely observers but active participants in the live music event.