1. The average vegan diet is safer/less deficient than the standard american diet. Most major diet orgs agree a well planned vegan diet is appropriate for all stages of human life
2. The cheapest foods are vegan - grains, legumes, starches. and they get you the majority of the way to a balanced diet. It's not that hard or expensive to get from them to a 100% well rounded diet
3. Just let the grazing animals live please. Live and let live, so long as it harms none do what you wish, etc. Buffalo/etc don't need humans to make them go to certain spots to graze
4. most crops go towards feeding animals in animal agriculture. Less crop deaths is better, so if you actually want to reduce them you should go vegan and/or grow your own food

i agree that many vegans have wacky/woowoo/incorrect beliefs and it's a real shame, but a broken clock is right twice a day