@Catchlt is correct. Breeding has produced horses for for the purpose of racing. Its done very specifically, thats why you pay for breeding a dam from a well performing stallion or the progeny they have sired.
Racehorses are expensive. Not just for the horse, their upkeep and training. I can think of a lot of horses that get better treatment that I do. No one brushes my hair or rubs my back every morning.
There are a number of charities that re-home ex racehorses. The difficulty is that where they have been trained for one thing it can be incredibly difficult to try and re-school them. A TB can be amazing at dressage for instance, but trying to 'reprogramme' them so to speak to basic flat training can be a nightmare. I was given a mare to school (sire and dam were racing horses) and I couldnt do it. She literally just wanted to bolt at every chance and I saw more than my fair share of hedges after she chucked me off!
TBs can also have a lot of health problems due to inbreeding to get that 'perfect horse'.
The horses you see on TV are not neglected or abused.
I dont want to get into the 'ahhhh racing is cruel' debate, but would like to point out that there's a hell of a lot more to racing than a race you see on television.
I respect that some people find racing to be offensive, that is their right. As a person who has grown up amongst many different horse- related disciplines, I disagree.