The same way a dressage horse's neck goes to pot because of rollkur
The same way hunting horses break their necks and backs falling into ditches. You won't find stats on this because they just drag them out and send them to the hunt kennels.
Will we even go there on bronc riding?
I'm well used to do "anti-racing" people. I don't care which sport people compete or have interest in, everybody is different and the world would be a boring place if we all agreed on the same thing.
As used to it as I am, I do get annoyed with people believing we are these big bad horrible people rolling in the cash who couldnt give a toss about our horses. Videos like that create a witch hunt, if PETA and SHARK had their way all ponies would run free with no riders on their back and live happily ever after.
Again, all equine sports have "bad people" in the industry who cut corners or do crazy things that end up hurting or killing horses. Racing is not a BAD sport and niether are any of the others, it's the fact that hunderds of horses are killed every year because greedy people are in such a hurry to make money they aren't concerned for the horses welfare.
Perhaps it's just me, But a horse blowing out it's whole leg and still running while bone fragments shatter every where is a much more gruesome and horrific event, compared to rollkur, and neck or back breaking. Of course that same type of blow out can happen in any sport, if the rider is idoitic enough to think running at that speed is safe.