Why J.D. Salingers 1951 novel The Catcher in the Rye ever been made into a movie?

J.D. Salinger's 1951 novel The Catcher in the Rye has never been made into a movie. Salinger was famously protective of his work and refused to sell the film rights to the novel. There have been several attempts to adapt the novel for the screen, but none have been successful. In 1968, Salinger rejected a proposal from director Elia Kazan to adapt the novel into a film. In 1979, Salinger also rejected a proposal from director Steven Spielberg to adapt the novel into a film. Since then, there have been no other serious attempts to adapt the novel for the screen.