RE: The most backward, primitive and uncivilized entertainment. Talk about the lives of thousands of animals?
Even when you remove the use of physical or emotional pain from the equation, the morality in the interaction between humans and other animals is not clear.
Even "humane" training/domestication of animals (such as horses) still produces creatures that are alienated from their own nature. If you have seen the eyes and demeanors of wild horses, as I have, you will be aware of the life and alertness you see. Compare that to the eyes of horses that have been domesticated for "riding" or for farm work.
Although I eat eggs a lot, I try to buy them from free range chickens. I think it is better for my physical health and for my spirit. The same goes for wild caught fish as compared to farmed fish. And, although I am not sure of the morality of "breaking" horses for riding, I have managed to reconcile myself to the fact that I myself have been domesticated by parents and society and I am thus far from being in the natural state of an uncivilized human. Therefore I forgive myself for riding horses :-)