That's true, but on the other hand you get a much bigger nutritional boost out of eating the beef - it's rich in protein and other things that we need to live, which can't simply be replaced with more carbs. I'm not a big consumer of beef and I agree with your general point, but it's not the 1:1 equivalence which would mean 7/8ths of the beef someone consumes is a waste.
I do not eat meat and I do not have to eat more food than I did when I did eat meat. You've made a statement of fact, but it's at best highly ambiguous, but probably just outright false. You're confusing a bunch of nutritional concepts and coming to a non-sequitur conclusion.
That's not what I meant at all - there are plenty of other non-meat sources of protein, from cheese to nuts, depending on how vegan you are. Once again, what I'm taking issue with is the notion that because 8 units of grain are needed to provide 1 unit of beef, the units are nutritionally identical. Making weight for weight comparisons as above is what's a non-sequitur.
Getting such comparisons fully correct is certainly hard, but I don't think it goes the way you think it does in this case... looking at a few different specific possibilities for "beef" and "grain", the "grain" looks to usually be nearly twice the calories of the "beef" per pound. Humans do not actually need huge amounts of protein and there is rarely a (medical) need to go out of your way to get protein no matter what your diet is.
