Why Lie in a Memoir?

I know this blog is a little late...I was a little out of it from having my wisdom teeth pulled, but this morning I came across a story about an author, Constance Briscoe, who is defending her autobiography. Her book, called Ugly, is about her childhood growing up with her abusive mother and father. She writes that her mother used to starve her and abuse her physically and her stepfather once put a cigarette out on her hand. She then writes that her mother abandoned her at the age of 13. Briscoe's mother, Carmen Briscoe-Mitchell is suing for damages against Briscoe and her publisher Hodder and Stoughton.
Now my question is why would someone write such an awful autobiography and it not be true? I mean allegations of abuse from her parent's are crucial. Perhaps because, as gory as it is, the public responds to painful and hurtful autobiography as opposed to a happy and peaceful one. I mean if you think about what's in the media right now, it's not that surprising that IF Briscoe is lying about her childhood being so awful, it's because she wants it to sell. I think most people know of the story about Jennifer Hudson, the American Idol runner up. Her family was practically slain. The story is so sad and awful AND very popular. It has people talking about her and how she must feel.
Perhaps what Briscoe was thinking when she wrote her autobiography, if it isn't true, is that people would respond more towards a sad and painful life and not a normal and happy one. While there are all types of stories, happy and sad, in the media, its the ones that tend to have a more painful side to them that I pay more attention to. If my mind is like that what would make me think that an author who wants to sell a book doesn't have the same mind set as well? I'm not saying that her book isn't true, I'm just saying that I can see both sides to this case between Briscoe and her mother. There are also other cases in which authors have said to have written their autobiographies but it turned out to not be true.
"One of the most notorious cases involved Belgian-born, U.S.-based writer Misha Defonseca's 1997 book, "Misha: A Memoire of the Holocaust Years," an extraordinary story of a child's survival during the Holocaust that was translated into 18 languages and made into a French feature film.
Earlier this year Defonseca admitted that she had never lived with wolves to escape the Nazis, as the book claims, had not walked 3,000 miles across Europe in search of her parents -- and isn't even Jewish. "
I feel as though the media picks up on the fact that the public is more interested in reading about struggles and hard times(as much as they won't admit it) and authors pick up on that and may write about fake hard times to make a dollar.