Former British champion Bill Hartston once observed, "Chess doesn’t drive people mad. It keeps mad people sane." Morphy and Fischer’s behavior became truly bizarre only after they retired from the game.
That is from Paul Hoffman’s King’s Gambit: A Son, A Father, and the World’s Most Dangerous Game. I loved this one, it’s one of the few great chess books. It’s also a tale of how Manhattan has changed, how sons become independent, the nature of psychological warfare, and why obsession never really dies. Note that author Hoffman is also editor of Discover magazine, which I enjoy as well.