Do you believe the 80 billion land animals (so excluding fish, who are also sentient and would rather be left alone) killed each year are all or mostly killed without sensing fear or panic at any point in their upbringing?

That sounds like a Nirvana fallacy.

The killing is still unnecessary

Even if it were, youve admitted there's no real issue with mass murdering countless animals in order to grow plants. What are they going to do, take us to animal court for eating beef but not for running them over with a combine harvester and leaving them to slowly bleed out in a field next to their litter of young? lol

You know this somehow?

Yes. They lack the cognitive capacity to want those things. Are you saying you're as smart as a cow?

So why do we do it?

For food. I thought that was clear.