Many of them are actually pretty passionate about their work so unfortunately they will always be exploited because capitalism punishes people who do something they care about or otherwise enjoy.
The slur is “self righteous pricks” when they behave like the above. I say this as somebody who thinks vegans get a very unfair, underserved bad rap. People like the commenter above give all of them a bad name even though I find most vegans are just trying to live their life their way and don’t lecture folks.