A better answer is hiding in your posts. It's that: We believe that humans, even criminals, have dignity and should be treated decently despite their wrongdoings. The argument, then, is that we could extend that "deserving of decent treatment" to animals.

It doesn't need a billionaire to make this happen (which is why you're confusing me), it just needs culture to change.

My question I guess is this:

Does unregulated Capitalism have the mechanisms to abolish such things with time? If there remain even 10% of meat eaters who want to pay $1 for a hamburger, who can stop the factory farms??

The only thing I can think of is a billionaire buying all the animals the way slaves were redeemed for money in some countries. After that no competing farms could start because they wouldn't have the animals to start with.

Of course. That's why you need regulations, not billionaires, in both cases.

So can advocates of capitalism admit that it needs to be regulated? How would factory farms have been abolished under anarcho capitalism? How would child labor or sweatshops be abolished? They say that under the NAP there would be no coersion, but clearly there is.

They say private ownership of animals will prevent their extinction, like commercial bees. That may be true but what about their welfare?