He was also a director of Hinckley Yachts. Bain was a longtime trustee of several children’s charities in Boston, including Children’s Hospital Boston, The Boys and Girls Clubs of Boston and the Posse Foundation. He also served on the board of trust of Vanderbilt University. and was a trustee of the Naples Children and Education Foundation in Naples, Florida from 2002 until his death. He had a brother named Larry. He had four children: William III, Adam, Alexander, and Samantha. He resided in Naples, Florida, with his third wife, Ann Dean Bain, to whom he was married for more than 20 years by the time of his death. Bain had been suffering from Alzheimer's disease and died on January 16, 2018 at his home in Naples, Florida, at the age of 80.