You seem to be conflating carnism for the carnivore diet. Info on what carnism is can be found here [0]. There's a lot of good stuff in that article, I think! Unfortunately, there are people who are indulging in a pure carnivore diet. You're right that it's patently unhealthy, and frankly it's a little weird.

Veganism is a subset of vegetarianism. I'm trying to be flexible with my position to allow for good discussion - being either vegetarian or vegan is typically healthier and objectively better for the environment [4].

Recognizing that humans are omnivores also means that by definition we can sustain ourselves solely by plant or animal matter [1]. Your statement of "Making a conscious decision to go against biology [...]" is plainly inaccurate, as we are quite capable of living healthy lives without meat.

There is plenty of evidence to support the fact that animal agriculture is harmful to the environment [2][3]. In fact, it is the second largest contributor of green house gasses.

I get the sense that there is some frustration coming through in your thoughts. Please keep in mind this is exactly how cognitive dissonance expresses itself. Take a breath, check out some of the citations below, and try to think about this data with an objective approach.

0. https://en.wikipedia.org/wiki/Carnism

1. https://en.wikipedia.org/wiki/Omnivore

2. https://ehp.niehs.nih.gov/doi/full/10.1289/ehp.11034

3. https://climatenexus.org/climate-issues/food/animal-agricult...

4. https://pubmed.ncbi.nlm.nih.gov/19562864/