1. Grass does take up a huge area. What would you do with that area considering it's too dry or too infertile to grow anything other than grass, and it can only manage grass when there's animals fertilising it
2. Any grass eating animal makes methane. Rot on idle land makes methane. If all the cows were killed deer would equal their biomass quickly. Cows are managed and there are plans for modifying their microbiome to completely process their food to CO2. This is the same weight of carbon that the grass regrows. Methane effectually breaks down to CO2 so castle are carbon neutral, but the time as methane is a problem
3. Animal welfare. Indeed a long list. I would love to see many types of animal agriculture banned. Some are far too cruel for a wealthy nation
4. I don't believe you.
5. I'm not saying everyone must eat only meat, and lots of it. Why should I be restricted from what you can't afford?

It is necessary to eat animals of you wish to thrive and do not wish to take supplements. Look up the list of what vegans sold supplement to be healthy; it's a much longer list than a person on a mixed diet

Mixed diet required supplements:

; empty list

Vegan required supplement list:

• Vitamin B12
• Vitamin D (unless you produce enough cholesterol and get enough sunlight)
• Long chain omega 3 fatty acids
• Iron
• Calcium
• Zinc
• Iodine

According to https://www.healthline.com/nutrition/7-supplements-for-vegans#6-Zinc

I would add creatine to the list, since it's seeming more and more important and only occurs in meat.

Funny that herbivores don't need supplementation, but we do, even though we can eat so many different plants than most herbivores.