Racing itself is not cruel . Its the Industry surrounding it that is cruel. As soon as big money is added to any sport involving animals it becomes cruel.
How on earth can you say, as a horse lover and rider, that breaking in a TB at 18 months old (usually horses are broken between 3-4 years old) is not cruel -their bones have not even set' yet. They do this because a horse not racing is a waste of time and money and they want to get them on the track as soon as possible.
Over the years horses have got lighter in build, bred for speed, even the NH horses. We are now seeing NH horses bred like flat racers, this is why their limbs break more easily -they are going far too fast into fences a lot of the time.
A big mistake is to anthropomorphize animals . Animals are concerned only with three things -to eat, to breed and to keep themselves safe. They do not 'enjoy' racing -they do it as its a natural instinct to run with the herd.
Most failed racehorses end up on French dinner plates -the unlucky ones end up owned by people who have not a clue and are kept inappropriately.
My horses are now retired but I did Endurance riding with them -they 'enjoyed' getting out to fresh places and getting excited running with other horses -but equally would be happy, as they are now, in a field being well looked after but not ridden.