I'l never understand people

Surprisingly enough, my sociology textbook actually said, "There would be enough food to feed 10 billion people if everyone adopted a vegetarian diet." I was expecting that this either would not be mentioned in class, or would be met with nothing but disbelief. Instead my teacher actually did bring this up and he said "I don't know about you guys but I'm not willing to give up meat." The rest of the class agreed.