Roy doesn't need publicity or money, but he does need some confrontation
It's one of the more perplexing questions of modern times.
What makes rich, successful, admired people write biographies, claiming that their aim is to "set the record straight", when all it does is allow them to settle a few old scores, and thereby reveal them to be sad, bitter men?
It's a question given greater pertinence by the convergence in Dublin of two exponents of this unwanted art.
By a remarkable twist of fate Alex Ferguson will give a speech in the city centre today, on the exact day that Roy Keane launches his new book a few hundred yards away.
And it surely can't be long before the former Man Utd manager responds to the criticism of his former protege, who on the asterisk-laden front page of a newspaper this week described Sir Alex as a "F***ing Pr**k".
In the second instalment of his memoirs, Roy describes how he has always been uneasy with being in a comfortable place, and has often sought out confrontation just to mix things up.
"That's the self-destruct button," he explains. "Things might be going really well, and I don't trust it: 'It's not going to last,' or 'Why am I getting this? I'll f**k things up a little bit, then feel better myself.'"
And it's not hard to agree with Roy on this matter.
After all, just as his career as a manager was being rehabilitated with both Ireland and Aston Villa he goes out and writes another book, with the inevitable headlines about fighting, boozing and bitterness.
Roy doesn't need publicity; he doesn't need respect; he most certainly doesn't need the money - it's almost like he needs the confrontation.
"F**k things up a little bit", Roy? Well congratulations, because with this book, you've done it all over again.