Almost all celebrities that put out a book, use a ghost writer.. They haven't the time needed to do it themselves... Just time to spend a few days during their scheduled duties discussing history, and principles... There are sometimes boxes of info provided..
Although no one mentioned it, these "ghost writers" are well compensated.. A friend makes a great living as one. He and his wife are spending the winter in New Zealand and Australia this year, writing and sailing..
I read lots of biographies, and I think I'm able to get a better feel for the celeb, when a ghostie, who knows how to do it, goes to work..