Good points. There is an element of narcissism to it. Most extremely health-conscious vegan I knew, obsessed for 20 years. Then was diagnosed with MS. You would think she’d keep obsessing, but like a mugged lib, she reversed course and started eating liver.
Don’t know how it turned out for her, we lost touch. But in retrospect, she was a world class narcissist in those days. Except about nicotine!
My daughter is a vegetarian, not a vegan, and she eats fish which makes her something else that I can’t remember right now.
She never mentions it to anybody, just quietly does her own thing.
I think the thing that annoys us about vegetarians and vegans is their self-righteousness.