This is just zealots like any belief. It is not all vegans. I have been vegetairian for 30 years amd vegan for about 3, other than responding to you I never "promote" my life choice to anyone or try to convert anyone. It only comes up if a coworker say he lets grab dinner and I order a tofu curry while they have a steak. I even worked at a place for over 5 years before finding out a fellow employee was vegan. It just never comes up.