They are a small, harmless minority. Isn’t that enough? Maybe it’s made worse by the fact that they are perceived as non-violent and effeminate, because of their strong opposition to suffering, even when the victims are helpless, like animals. There is no personal risk in bullying them. It’s like the hate for environmental activists, trans-women, or liberals in general. I wouldn’t know that vegans aggressively proselytize their life-style if people didn’t aggressively tell me so; something that they share with “the gays”. Of course, people wouldn’t mind if they didn’t shove it in their faces all the time. Where have I heard that before?