I was under the impression you aren't overly concerned with factory farming methods. What's your opinion on the report about the dog?
You're conflating two completely different things. Psychopaths tend to start off torturing animals and then move on to bigger creatures. They've already got something wrong with their heads.
Slaughterhouse workers start off as ordinary people and eventually come to view cruelty as normal or as entertainment, because they're exposed to it day in, day out. A bit of googling with throw up plenty of case studies. They don't, however, become psychopaths; nobody really knows what causes psychopathy, but it's most likely a genetic fault.
It's worth pointing out that people often end up working in meatpacking facilities because they think they have no choice. In a lot of bumfluff towns in the middle of rural America, it's a slaughterhouse/meatpacker facility that provides 50% of the jobs. That's one reason why legislators bend over backwards to accommodate their faulty business model. All they see are jobs, taxes, and votes.
Also worth pointing out that a large fraction of their extra costs are imposed by vindictive government rules that favour big operations, such as the inspection requirement. If that weren't so, CAFOs would be even more uneconomic than they already are.