That's a weird statement. When is "movement size" ever a good indicator of truth?
Anyway, veganism is not about "veracity", it's about a different set of moral beliefs, or a particular diet, or...
You speak of vegans as if it was a monolithic group, and you paint it with a negative brush because of a few crazy individuals. That's like dismissing entire religions and countries because of a handful of fanatics.
Meanwhile, as vegans focus on the elimination of meat from our diets, they practically ignore the industrialized food that wreaks direct reproducible havoc on our metabolisms causing epidemic obesity and diabetes.
Really? All of the vegans I know care a lot about eating a balanced and healthy diet (at least, more than the average non-vegan).