Change my mind:)
Vegetarians have existed like for ages. One of my mother's friends was (and still is) pretty much a pescatarian, though she eats chicken liver sometimes for the vitamins. In India, some areas have been vegetarian for centuries, even without modern supplements this diet seems sustainable, though a restrictive one.
On the other hand, even 20 years ago few people heard about vegans. Yet now, if you try to do a search on vegetarianism the only thing you come across are militant vegans.
Vegan diet isn't sustainable in the long run without supplements (at least b12) and many quit and go into the other opposite, pushing meat-only diets.
Those behind this psy-op have probably heavily invested in both vegan products/supplements and meat industry and thus profit both ways, while sensible folks interested in vegetarian-leaning diets are scared away by the fanatical vegan rantings (and horror stories of ex-vegans).
Others, especially gullible young women decide that vegan is the way to go and more often than not destroy their health and fertility, while making the vegan industry rich, then often turn to the other extreme, as I mentioned above.
It's interesting that vegans often attack vegetarians more than omnivores, calling them traitors and such.