After establishing trust funds for his wife and children, Zell Kravinsky is living on $60,000 a year so he can give most of his $45 million real-estate fortune to charity. He has also donated a kidney to a stranger. Studies show that the odds of dying from the procedure are about 1 in 4,000; Kravinsky claims he can't justify valuing his life at 4,000 times that of a stranger.