Why did John Travolta not play in grease2?

John Travolta did not play in Grease 2 because he was already a major movie star at that point, and he had no interest in reprising his role as Danny Zuko. He had also moved on to other projects, including Saturday Night Fever, which cemented his status as a leading man in Hollywood.

While Grease was a huge success, Travolta was keen to pursue other roles that would challenge him as an actor. Grease 2, while a commercial success, wasn't critically acclaimed like the original and wouldn't have provided the same level of career advancement for Travolta.