There's also the significant cost to climate change because growing crops to feed to animals instead of eating crops directly loses the majority of calories, but it gets ignored because doing something about it is going to be unpopular:

https://ourworldindata.org/global-land-for-agriculture

> More than three-quarters of global agricultural land is used for livestock, despite meat and dairy making up a much smaller share of the world's protein and calories.

> Despite the vast land used for livestock animals, they contribute quite a small share of the global calorie and protein supply. Meat, dairy, and farmed fish provide just 17% of the world’s calories and 38% of its protein.

https://ourworldindata.org/land-use-diets

> Livestock are fed from two sources – lands on which the animals graze and land on which feeding crops, such as soy and cereals, are grown. How much would our agricultural land use decline if the world adopted a plant-based diet?

> Research suggests that if everyone shifted to a plant-based diet, we would reduce global land use for agriculture by 75%.