I saw your comments further down but I want to reply here because some people do sometimes make this argument in seriousness:

Like others said, if I could get all my nutritional needs met synthetically and/or photosynthetically (and still be healthy) I would be happy to. But as it stands, going entirely plant-based is the best and most practical way to minimize harm to all life - including plants. To consume animals you need to raise them, and it takes significantly more plants to raise an animal for food than it takes to eat the plants directly.