You know, it's kind of funny. Horses might have a better argument than any other animal for being the natural predator of humans. Specifically, nomadic depredations on preindustrial societies comprised armies with a proportionally small number of humans and a large number of horses pillaging towns and cities full of horseless humans. In 13th-century Asia, the average horse probably had a better life than the average human. The same thing happened shortly after the horse was (re)introduced to North America in the sixteenth century; settled agricultural societies were quickly overrun by horse-riding nomads.