Overlay by Barry N. Malzberg
Some aliens decide to destroy the earth by focussing on a certain group - those that bet on horses. What follows is more of analysis of people that bet on horses than science fiction. One guy is pretty much of a loser, and likes to bet on horses. He loses a lot, and doesn't really win because that would force him to make decisions on move on with his life. It seemed like an interesting concept, but was not well executed.
