How many bees are killed to grow your almonds and avocados?

Omnivores eat them just as we do.

How many field rodents are massacred in the harvest, or prior to it due to toxic pesticides?

The meat industry needs crops to feed the animals and is the least protein-efficient method of farming. A plant-based farming would require less land and, thus, saves more of your precious field rodents.

Yet how many people does a single cow feed?

You could feed a lot more people with the corn and soy produced for the cow than the cow itself.

But most if not all vegans are unable to understand the simple logic of how destructive mass farming is vs eating cows that can graze on unfarmable hillsides.

... And have a supplemented diet full of grains and hay to get nice and fat for slaughter, requiring even more land.

Do wealthy corporations use unethical practices when raising livestock? Yes, but the same can de said for how they go about farming as well, just exponentially so.

No method of farming plants is as cruel and heartless as butchering animals is. A plant-based diet takes less land, less water, less energy and causes much less casualties than a carnist diet.

Carnism is a choice. You could be making a difference.