GM Michael Wilder (born August 17, 1962) won the title in 1988 but then enrolled in law school at the University of Michigan, and his chess career was over. In an interview he stated he had neither the energy nor the motivation to keep his skills sharp. His USCF rating was 2601 while his FIDE rating was 2540. Plus, Wilder wanted to be a family man and that required money that was not avaiable as a chess player. These days Wilder is a partner at McDermott Will & Emery in Washington DC where he specializes in corporate tax issues. He is also an adjunct professor at Georgetown Law School and teaches a class on advanced international taxation.
I posted on GM James Tarjan, another loss to US chess, back in 2011. Tarjan recently retired as a librarian and successfully returned to tournament play; hopefully he will continue to play for a long time to come.