Growing plants to feed animals and then eating the animals is a highly inefficient way of producing food, especially when we can get all the nutrition we need by eating plants directly.
Animal agriculture uses over 80% of farmland, but produces only 18% of calories and 37% of protein.
Even when animal-based food is not “wasted” in the traditional sense, i.e. not thrown away, it creates more environmental issues such pollution, GHGs, soil degradation, and uses higher levels of resources such as land, water, fossil fuels than plant-based alternatives.
So why base your diet on something so resource intensive when there are perfectly viable alternatives that don’t have such a negative impact. Why choose the least efficient option which is inherently more wasteful? We would be better off not producing such wasteful products altogether.