Elephants spend 12-18 hours a day eating,[1] compared to 68 minutes on average for an American human.[2] Is that what you want for me and your children?

[1]http://www.nationalelephantcenter.org/learn/#:~:text=Since%2....

[2]https://www.foodnetwork.com/fn-dish/news/2015/07/guess-how-m...

Yet vegetarians don’t eat for 12-18 hours a day. You do know they already exist?

How much is that reduced if you cook the vegetables? Or do you eat raw meat? The time spent eating is a function of nutritional density and difficulty to digest. We have plenty of nutritional vegetarian food that doesn't require hours of chewing to extract the nutrition from.

It's an interesting counterpoint but not actually proving the point made. There are large herbivores.

And lions spend 20 hours a day sleeping... what's your point?

They can sleep 20 hours a day because they only eat once every four days. If they had opposable thumbs they might do something else.