> Is it really unethical to eat animals when the natural trajectory of most animals lives was likely to be eaten by other animals or die some horrendous death

The vast majority of meat that we produce isn't sparing animals that would have died anyway, it's not from hunting. We bring animals into existence (lots and lots of them, more than would naturally exist) for the sole purpose of killing them. Whether or not that distinction resonates with you morally -- different people have different reactions to that. But for me, it feels tangibly different.

I also think about it from an individual perspective instead of a societal perspective. I stopped thinking about a binary "is it ever wrong to eat meat in any situation" question, and the question I started asking instead was "do I need to?" The answer to that question doesn't change just because of what the food chain is, or what animals would do to me if they got the chance, or what tigers do in the wild, or whether deer like being eaten by wolves. Those systems might exist, but do I need to be a part of them?

Nearly all life on earth exploits other life to live. Humans aren't an exception to that, I'm not an exception to that. But if I can reduce my level of exploitation at little cost to me, then I want to. I don't buy that I would be killing animals as an act of charity, I know myself too well. For me personally, I can't pretend that I was eating chicken because I cared about the animals.

> Isn't it better for an animal to live its best life on a free range farm being grass fed, then get quickly and humanely slaughtered?

I don't think this is a scalable model for food production. My personal experience has been that choosing to eat only ethically sourced meat is more expensive and more difficult than going vegetarian. And I am doubtful even in a perfect world that free range farms with humane slaughterhouses would be capable of providing the amount of meat that people want to eat today. I think in order for that to happen, at the very least a lot of other people would need to go vegetarian or significantly reduce their meat intake.

What you're asking is a complicated question, and different people have different answers to it, and even saying something like "killing animals is unethical" is itself a really broad answer that means different things to different people. But I feel reasonably confident today saying that inhumane treatment of animals is built into the agriculture industry at a very fundamental level, and I sort of think it's naive to say that's going to change. I see more people becoming vegetarian at a faster rate than I see people opting to find a local farmer that can supply them with local free range beef. And as uncomfortable as it might be to say, most of the meat you see in a store came from animals that led horrible lives before they were butchered in horrible ways.

So on some level, I feel like the underlying ethical question of "do animals exist for food" is kind of besides the point, because even if they do exist for food, I don't see any evidence that we can keep meat production going at the same rate and at the same cost without being cruel to animals. I see a lot of people who want to believe that we can do free-range happy cows, but... everything I know about economy of scale contradicts that idea.

> If I made a personal decision to stop eating meat, would there be any significant impact at all on the overall environment realistically?

Maybe people can debate this, I can't say with certainty that insulating your house really well or reducing driving wouldn't be comparable in some cases. But most information I have seen suggests to me that for most people, eliminating meat (or even just reducing it) is one of the single highest-impact actions any individual can take for their own lives. So if you are looking for ways to reduce your personal environmental impact, then yes, reducing (or eliminating) meat does help at least as much as anything else you can do.

But, let's get to the rest of your question:

> However, the reality is that me (not) eating a bowl of sashimi once a week makes no difference in the context of, say, countries like Japan slaughtering millions of fish daily

Correct, but here's the thing. Literally nothing that you do to reduce your own individual emissions is ever going to be significant next to the impact of industry and government. You sort your plastic, great. The impact of doing that is negligible compared to a single bill that regulates how water bottles are made.

What makes vegetarianism promising is that there is genuinely a social shift happening on a wider scale than just with individuals, and that social shift has impact on industries. The biggest environmental impact of vegetarianism is when enough people shift that the meat industry overall starts to pivot or produce less meat, or where enough political pressure builds up that meat subsidies start to go away. The other thing that makes vegetarianism promising is that the more demand there is for meat substitutes, the cheaper those products become and the more resources are devoted into developing better products.

We saw a similar thing happen with green energy. Individual choices meant very little compared to the amount of energy that industries used. But at some point, green energy got cheap, and demand got higher, and companies started getting into it as well.

So I am cautious about telling people that what they do doesn't matter, because a lot of this stuff only changes when a certain threshold of people start getting involved or putting pressure on politicians to make changes. I don't want to pretend that reducing your own emissions is going to save the world, but I also disagree with the fatalism that says that individual choices don't matter.

I don't know if vegetarianism has enough momentum to significantly reduce meat demand, but it might. And when I look at the alternatives, I don't think there's any chance at all that the ethical meat movement has enough momentum to change anything, so throwing weight behind the vegetarians is about as good a plan as anything else. Beyond Burgers might get cheaper than normal burgers at some point, and that could drive a large change in how restaurants source food and how normal people buy food. If enough people stop buying fish, commercial fishing might go down because of a loss of profits. But there is basically zero chance that free-range chicken eggs will ever be cheaper than caged eggs, or that fisheries are suddenly going to become sustainable out of the goodness of their own hearts.