When Great Directors Get Senile

I think I have figured it out. Great directors get senile at age 55. This is when they create either extremely poor or preachy movies.

George Lucas, The Phantom Menace, age 55.

Steven Spielberg, A.I. Artificial Intelligence, age 55.

James Cameron, Avatar, age 55.

The lesson here is enjoy your great directors while you can. By my estimates, Christopher Nolan (The Dark Knight, Inception) has 15 years left before he makes self-indulgent crap. 5/4/15 update: Christopher Nolan is 44 and is already showing signs of senility, and I'm not the only one to notice: https://youtu.be/nyHgAPTsBJY?t=20m41s