Why is Holden the biggest phony?

Holden is, ironically enough, the biggest phony of them all. He believes that adults, and his parents in general, are phony because they must move forward with their lives, even beyond tragedy, loss, and other obstacles that life throws their way.

He calls his brother a phony because he writes screenplays and not serious books, and yet Holden can't seem to stay enrolled in a school. Holden can see everyone else's faults but his own and that is a type of phoniness in itself.

Holden refuses to grow up. This is phony. A young adult still acting as if he is 12 is phony. This is evident in the way he treats people. He says he likes Jane but when it comes to calling her or connecting with her, he refuses to do so.