Reason of the day not to write a memoir

About four years ago I went to a panel discussion event at the New Yorker Festival where four successful writers of successful memoirs sat on a stage and answered the pompous questions of Bill Buford, an insufferable twit who insisted on pronouncing the word "mem-wah." Dave Eggers was humble and mumbly, Frank McCourt was jovial and glib and Martin Amis, eyebrows raised and mouth squinched, was doing his best to put up with the whole undignified thing. Mary Karr, though, was extremely sensible. She said:

"People always tell me they really want to write their own memoir, but they can't really remember all those details. And I say, 'If you don't know what happened, why the hell would you want to write about it? Why the hell do you think you could?'"