I still think that this is a tribute to fashion. One has only to put the vegan in conditions of survival and he will forget about this fashion. The substitution of meaning by fashion is fraught with various deviations, but we are people and fashion influences us. especially if reputable acquaintances or friends eat this way.
Depends on the reasons for which the person became a vegetarian. If for ethical reasons, then the vegetarian also, for example, does not wear leather things. This is no longer just nutrition, but a philosophy with a practical component.
If for health reasons, it is rather only nutrition.
If for a person food is one of the main components of life, then, being essentially nothing more than a food system, vegetarianism is also a lifestyle. So, probably, it is - vegetarians, as a rule, attach exaggerated importance to nutritional issues, both their own and those of others. "Tell me what you eat and I will tell you who you are."
Philosophy, religion, zoolatry. We worship animals. Seeing them, we kneel, bow and adore.
But seriously, everyone chooses for himself the reason for refusing meat. I got interested, and I was addicted. And you know, I don't regret it at all.