It would be helpful to add the total number of meals consumed per unit time as well, and perhaps the number of humans born/dying.
We eat a lot because there are a lot of us.
We eat a lot because there are a lot of us.
I am rather more worried about hungry kids than dead cows.
I also don't care if people can subsist solely on vegetables; subsistence is not our aim -- we can live in appalling conditions, but we got out of those circumstances deliberately. It took a great deal of time and hard work in miserable environments to do so.
That's why there's so much meat now, we were tired of being hungry and we built a better world.
We have build such a peaceful, prosperous world now that large numbers of people are worried about the emotional state of our meat. They're not worried about hunger or violence or poverty because, for enormous numbers of people, those issues are gone. So now we worry about chicken burritos.
Sorry to break it to you, but humans just aren't that special.