Patricia:
I've known quite a few people who've trained and raced greyhounds. Some of them have been extremely caring. (They'd look after their retired dogs for the rest of their lives or ensure, usually through a recognised charity, that they found good homes. They'd also treat their dogs as much-loved pets). But, as you suggest, there are plenty of cruel owners out there.
The guy I found most difficult to comprehend was the father of a lad I used to teach. His son was an extremely able 14-year-old student (who could well have gone on, with sufficient parental support, to study mathematics at university) but his parents seemed to have no concern for him whatsoever. (He'd been sent to school wearing the same clothes for weeks upon end, with the inevitable 'personal hygiene' odours that can accompany teenage boys). His father seemed to have no interest whatsoever in anything other than in breeding and training greyhounds, despite the fact that his son was severely allergic to dogs. Regrettably, there are some very strange people in the world :(