The Godfather Papers and Other Confessions Information
"I was forty-five years old and tired of being an artist. Besides, I owed $20,000 to relatives, finance companies, banks and assorted bookmakers and shylocks. It was really time to grow up and sell out as Lenny Bruce once advised. So I told my editors, OK, I'll write a book about the Mafia..."
It explains Puzo's reasoning for writing The Godfather:
"I have written three novels. The Godfather is not as good as the preceding two; I wrote it to make money..."