It simply boils down to this:
We don’t need these animals to survive. Human beings can live long, happy, healthy lives without meat and cheese. Literally all nutrients we need to live and be healthy can be found in plants, or manufactured and added to foods (which is how livestock end up with B12, actually)
So, with that in mind, really any amount of harm or violence done to these animals is unnecessary, and done for pleasure (taste) only.
People who disagree tend to think that we somehow need to consume animals, but that has been debunked many times. Or, folks often convince themselves that violence and suffering of a sentient being for the reason of pleasure is somehow not simply evil.
That’s generally the viewpoint of folks who oppose eating and hurting animals.
Even the “one bad day” argument doesn’t hold up well, because folks would still raise hell if I painlessly killed my dog as soon as it became inconvenient to have one, no? Or they’d still raise hell if someone was unknowingly molested in their sleep.
There is more to deciding if we are treating a sentient being well beyond simply “did I treat it okay before I killed it?”, and the only reason that’s hard to see is because most people on this planet grow up being told that for some reason, some animals are different. For some reason, we can bludgeon a pig to death with a hammer (thumping), or boil a living lobster alive, but we can’t do the same to a dog or a cat.
We have been lied to. Doing any of these things to animals is wrong because we don’t need to eat them, except in very rare cases.
If you’re ever on a desert island, we can have a different conversation.