This is the sad reality in the society we're living in. If the majority is siding with it, they perceive it to be good even though they know deep down that it's not. Perhaps it's conditioned in their mind that as long as they benefit from it, despite the consequences it has for others, it's all good. After all, they are not directly affected, only the animals. And this mindset is really upsetting. It's like humans have lost their empathy just for the sake of having fun and winning money.
Despite it existing so many years now, I do really hope it would be abolished together with other gambling activities and practices that hurts and put the welfare of the animals at risk. The technology and innovation is quickly advancing and we can do so many alternatives for it. Wishing they'll divert to those instead.
Ever since men stepped on this planet he is destroying the natives of this land be it animals on lands or fishes in ocean. There are many species who cease to exists just because human kill them for fun. I dont think there are many who are interested in horse racing but in gambling. Let these animals live there life just like we are living.
Well not all man are destroying the planet we live in. Most humans who hunts animals are mainly because of foods, money and survival. But, yes, you're right, the main reason why our planet are dying is also because of humans. Just imagine how much pollution we humans are making without even contributing any to control it such as cars, factories and many more.
Anyway, as per the OP's topic about most of us humans are still continuing with these kind of activities where we bet or gamble to these poor animals. Just as AicecreaME mentioned above, we are living in a reality which we are mind conditioned that these are normal. Not only with horses but also with other animals such as cock fights, dog fights and much more. These activities has been happening way too long and might have become a norm to others but it's a good thing that animal right groups and community are contradicting it and now has a voice. We might still hope for this not to be continued and be ended on the near future as there are so much more alternative.