Because of the amount of killing and injuries to the horses. The horses are basically used as slaves and then killed when they don't win or slightly leave their peak.
I find it strange people are out to get bull fighting banned in Spain but horse racing seems to get away with it. Probably because of the amount of money in the betting market.
Congratulations, you have supplied one of the most bizarre postings I've ever read on this forum.
Are you seriously comparing horse racing with bullfighting?
One activity produces animals to race which they do more successfully if they they are treated kindly and their medical, dietary and emotional needs are catered for to the best of training staff's ability.
In short they are pampered in comparison to almost all other animals.
Racehorses are not pets. We require something from them to justify the expense of their keep and associated costs. That requirement is that they race and maybe they are bred from.
The object of the exercise is that they will race for as long as they are up to the task and then an alternative use will be found for them.
This may be as a worker in another sphere, it maybe as breeding stock and the unlucky ones may lose their life but horses are not at the top of the food chain and they cannot thrive as a species without assistance from man.
They get a much better deal than 99% of other animals.
Would you seriously stop equine sports and accept the slaughter of all the horses who are currently part of this activity together with the severe economic concequences that would go with it?
Animals die for reasons other than old age. Let's ban cars to save the life of dogs, cats, squirrels and pigeons.
I am neither for nor against bullfighting by the way. I would not attend it but would not ban it either.