I've been vegan for about 13 years now.
I think it's a great thing for the health of the planet and yourself. I also think it's an ethical imperative since animals have the capacity to suffer. You can read this book if you want. Animal Liberation: The Definitive Classic of the Animal Movement
I manage a restaurant that offers a fairly impressive vegan menu.
Sometimes restaurants make mistakes. A guest said that the same mistake was made on her order three times on three separate dates, which sounds very strange. She claims she received real sour cream (instead of vegan sour) on the side of a vegan quesadilla. It makes me think that she might be perceiving our vegan sour to be dairy even though it isn't. But nonetheless, it was to-go order, so I don't have the luxury of finding out if she's right or wrong.
She got online to blast the restaurant on Yelp and Facebook, and here's where I think she hurts vegans. If you go online to blast a restaurant trying to cater to your minority view of the world, it makes restaurant people simply not want to cater to it. If my restaurant ripped the vegan menu out, it wouldn't even be a blip on our bottom line. We do it because it's a growing opportunity and because it's fun and interesting. We think it sets us apart from other restaurants, and we think it's a great way to contribute to a community. Also, some of us are vegans.
And if you blast restaurants making an effort to be part of the vegan community, you're hurting animals. When McDonald's finally gets around to offering something vegan, there will be stinkers like this lady making every executive there throw up their hands and say "fuck this vegan shit, let's just keep doing what we're doing; it isn't worth the trouble."