"I don't like LA. The majority just seem to be so artificial. Look at how they worship everything they think is fashionable. Isn't it sick?"

Billie Joe Armstrong is revealing his distaste for Los Angeles and its culture. He believes that most of people in LA are artificial and worship anything they believe is fashionable. He finds this behavior to be sickening. He is likely describing the superficiality of the city and its residents, and how they focus on materialistic products and patterns over more significant pursuits. He is most likely also criticizing the city's obsession with celeb culture and the idea that popularity and wealth are the most essential things in life. His quote is a commentary on the shallowness of LA culture and how it can be harmful to individuals who live there.