Thing is, life will find a way to survive despite our best efforts. We've seen mass extinctions before. Whether the human species survives is another matter.
It won't, but at least you're not part of the problem anymore. You might inspire other people to. And every person who goes plantbased makes it more politically viable to enact policies to encourage plant based over the most destructive other foods.
Try to avoid discouraging people who try to do the right thing, help them make a bigger impact instead.