I really think it's the worldview, with the caveat that this particular worldview, "x doesn't feel," allows people to exploit x without remorse. If everybody suddenly believed that x experiences love and pain, factory farming would make a lot of them feel really bad. I say this as somebody who thinks x does feel, still hunts x, and still eats x even when it's factory farmed. If I felt like my individual actions affected the market place enough to prevent a single individual from species x from being factory farmed, I wouldn't buy x from the grocery store, but I would still hunt it in the wild. Having spent half a decade as a vegan before ever hunting x, I'm pretty certain of my convictions there. I've grappled with this conundrum, and come to terms with it. I know an avid hunter who also grapples with this conundrum, and hasn't come to terms with it; he doesn't eat factory farmed meat on principle, loves hunting animals, and gets simultaneously really happy and really sad when he successfully kills one. "I acquired this duck," he says with a smile, "but it had to die," he says with a frown.
Edit: I'll add this quote from Upton Sinclair: "It is difficult to get a man to understand something, when his salary depends upon his not understanding it!"
Edit: I'll add this quote from Upton Sinclair: "It is difficult to get a man to understand something, when his salary depends upon his not understanding it!"