Do you actually think that there are zero costs for the upkeep of a racehorse. These donkey's are running at the bottom level of horse racing, they are geldings so have zero breeding use, it's like a car after running they are going to the knackers yard. With a bit of luck you might get Canned Corned Beef value when they mince them up.
Training, Jockey's, Feed, transportation to the track and the entry costs for a race cost a small fortune. These donkey's will struggle to get their costs covered. And then if the horse sustains an injury you're losing money bigtime.