Biologically speaking, we are FRUGIvore, not omnivore. Have you ever wondered why heart disease, type 2 diabetes and other chronic illnesses are so rampant in our society? It is largely due to INCORRECT diet.
Educate yourself.
There are MILLIONS of healthy vegans and vegetarians living all over the world, some including world class athletes such as Venus and Serena Williams, Lewis Hamilton, Patrick Baboumian, Novak Djokovic, Carl Lewis, David Haye, and Nick and Nate Diaz, all much fitter and stronger than the average bacon-loving meat eater.
It is scientifically proven that humans do not need to eat meat to survive (or thrive), therefore it is safe to conclude that you eat animals for no other reason than momentary taste pleasure and convenience. The sooner you are willing to admit that to yourself, the better.
Why those diseases? Insulin resistance, i.e. too much carb. And if we're frugivore, why can't we digest fibers like herbivores, and our stomach acidity is closer to a carnivore's?
Of COURSE we don't "need" meat to survive. But unless your meatless diet has enough saturated fat, you WILL die before, say, a clean keto eater