(Vegetarian here that only eats honey and eggs from a local farm but still feels bad about it) Western animal agriculture is bad, no doubt. I am totally convinced that a society which has animals as a part of a whole healthy environment in like a permaculture+animals sharing the space society can eat animal products and possibly even the animal in cases where it's healthiest for the entirety of the society including animals (think here of removing a male lion to allow a healthier population in total, but for goats that have been milked but live normal and free/safe lives). This would likely be temporary before becoming unnecessary if we reach a point past scarcity of proteins/foods. Max Ajl talks about this often (though he can be a bit chuddy about it, he's trying to protect pastoralists with it I think)

That seems really vague to me. A lot of things are bad for the environment.

I could see how it would be bad for the world, so the magical make the world vegan button would be pressed. I simpky see no reason to become vegan, or personally participate in any activism that helps animals.