There are far more sustainable protein options available, actually, than the consumption of other animals. There are multiple plant sources that not only have more protein, but are more cost effective and sustainable than animal sources. What it arguably comes down to is taste. Not many consumers are willing to give up their tasty burgers and that's likely never going to change unless we begin to bring up our children without the familiar tastes of animal products. If you feed a human plant sources in isolation from ever having a burger or steak, they will not crave these things. These are the things being advertised as "delicious" and satisfying. Also, you missed my point entirely, and I never said that other countries were not farming animals. My point was directed at yours concerning what these animals would live like if we didn't farm or breed them. Evolution didn't naturally select them for our consumption, one cannot logically argue that the cells of any primitive animal would be able to fathom the changes needed in order to become our common food sources today. There's a much bigger picture here, and one day I hope you catch on.