Is There a Primary Factor in Nutritional Factors in Veganism?

Some people just don't want to kill animals. There is certain, like, essential human nutrients that are only found in animal foods. When you don't eat those for years and years, terrible things happen. It's really as simple as that. But do you want to be making nutritional decisions based on non nutritiona factors? I mean, i would assume though, that would e the one. Lke, because if yo were living now, we want our kids to be able to have a beautiful earth still.