I guess they are hoping that the OTHER people in the pool will believe it, or forget about it before the 180 day limit to cash it comes.
http://usnews.msnbc.msn.com/_news/2012/04/06/11049946-self-declared-mega-millions-winner-mirlande-wilson-i-lost-the-ticket
OR Possibly she is aquiring a NEW place to live once she comes forth. (That was the path the people in my book took).