they may want to save the planet, but being vegan doesn't do that.

I do not disagree, but considering the meat-eating cultures, telling them to stop, has not exactly proved to be a winning move. The more working way seems to be, to get them reduce their meat consumption first. Then slowly convince them to take steps further... and even if that takes a long time, less meat is still eaten, so it is towards a better direction. Of course it would be better, if everyone would just stop eating meat right now. But that is still an idealistic take, sadly, especially with the meat industry having the lobbying money right now.

Whilst I understand your argument, if a strategy isn't working, pursuing it becomes more of a personal identity thing than a commitment to an objective.