I'm gonna be that vegan and take my downvotes for it, but... vegans largely object to a lifestyle that includes eating animal products because it's not purely a health issue. To me, and many in the vegan community, it is morally objectionable to kill a conscious, feeling animal mainly for your own pleasure, regardless of whether it is healthy, or sustainable, or raised with a pleasant life. Health is a less objectionable approach to converting people, overall, because people generally don't want to die, and pretty much nobody objects to the health benefits of eating 'enough' plant foods. Maybe you've had the experience that vegans focus only on health benefits, I don't know, but I think generally that isn't the biggest concern.