There are many more arguments both for and against that I’m not going to enumerate here, but are definitely available elsewhere in the forum. I’ll also plug that I agree with Henry’s comment—there are grassroots effects that are hard to measure, but my intuition is they have sneakily high EV.
But the main argument for me, and many other vegans (and vegetarians, but I’ll just say vegans for brevity) I know, is that at some point, they stop wanting to eat meat. If one truly views it as a chore, it will always be seen as a sacrifice. However, if the notion of eating animal products truly grosses you out, then it’s basically easier to be vegan than to eat meat.
I am not trying to deny that animal products can smell or taste great! But at this point, if I were to have a bite of chicken, the first thought for me would be “I am eating this factory farmed chicken that lived a horrible life of abject suffering” and not “hey, this tastes good.” It just grosses me out. Perhaps this would be a corollary to your point 5, but at some point, the dedication to the diet becomes more internalized. At that point, points 2 and 3 somewhat fall off, because it’s just a baseline lifestyle rather than part of my EA-aligned activities.
(To be clear, I acknowledge that this isn’t a universal vegan experience. I don’t mean to invalidate longtime committed vegetarians/vegans who don’t view meat the same way I do. I just mean to point out that there is potentially some light at the end of the tunnel that makes committing to this diet/lifestyle significantly easier. For me, that was about one year after transitioning from vegetarianism to veganism. Watching Dominion helped lock in any remaining doubts I may have had at the 1.5-2 year mark.)
While this is true, I also think it’s worth considering that this is often a criticism of any CEA, period. To the average person, the suggestion that a GiveWell top-recommended charity is more cost-effective than, say, a local food kitchen similarly requires estimates with error bars.
Yes, there are more assumptions when dealing with animals given welfare ranges, but I am reluctant to dismiss the analysis entirely because of that.
It is not immediately intuitive to me on what grounds one should value a human life more than that of a cow or pig. The moral weights project tries to put a number to something difficult to quantify. It’s not perfect, but it is better than nothing. (To be clear, I do value the human life more, but it seems unfair and speciest to do so.)