Racehorses are not worked to death, they generally have the best of life (for a horse). Trainers operate under a strict licence and any trainer abusing the animals face severe punishment. Racehorses are not run hard on the gallops, a heart attack can happen for different reasons.
The stable lads and lasses would not stand for a horse in their care (usually 2 or 3) being abused, it's a vocation for them and their horse's welfare is paramount. I think you probably know next to nothing about racing and the industry but you are being influenced by the emotion of seeing a magnificent beast at the end of life. As I said Gordon Elliott was very stupid doing what he did and he's paying for it.
The silly fuckers who used to do the "Munich" gestures were just as bad in my eyes but they're forgiven now and thankfully that behaviour is a thing of the past. Elliott should be allowed a mistake with punishment but it doesn't define who he is.