There is a lot of protein in non-meat products and the selection is getting better. Billions of people have existed just fine throughout the ages on a vegetarian/vegan diet. We evolved in a hunting Gathering way of life. Scientist have shown there was actually more gathering food sources than from hunting. Some people do have a problem with vegetarianism but most do not.
It is not so much the issue with killing as with the destruction to the environment, the problem with lots of chemicals in meat and the torture of sentient beings. Once I learned of the impact it became impossible for me to ignore the consequences of my diet.

I recently took a blood antigen test and my body reacts negatively to all dairy, eggs, soy sunflower and sesame seeds. Since I live on an island in the NW there is a lot of wild fish available and I do include some in my diet.

@JackPedigo
Fish, notably seafood, is your best bet for animal protein. Chicken is a second. Both can be raised and harvested humanely and without a bunch of hormones and other poisons. I'm with you there.
I'll agree that beef isn't well digested by people. But there's nothing wrong with fish, which can even be eaten raw.

@Leafhead First off it depends on the fish. Here in the PNW we just terminated the contract for a massive Atlantic Salmon fish farm due to the negligence of the company which allowed hundreds of thousands of farmed fish to escape. Some fish, like Rock fish live over a hundred years and don't start to procreate until they are in their 20's. Catching them earlier seriously depletes the stock and I have a problem killing an animal that lives so long. Here in the islands we do get wild Salmon and I eat some. Again, the issue of protein is way overblown. We Americans think we need far more than we do. Too much protein can be harmful.

It is primarily the Cattle and Dairy industries that are to blame. Again, big business.

I have seen the video and lots of others like it. Good luck trying to get the meat eaters to watch these things!!