Militant vegans hate themselves, and to better manage their self-hate, they project that onto others and hate everybody else, be it vegan, vegetarian or meat eater. They save their love and compassion for non-human things instead, i.e. non-human animals, be it herbivores, omnivores or carnivores.
I did a vegan diet for 1 year once, and 6 months at a different time (plus 6 months with a vegetarian diet immediately prior to the vegan diet), and I was like you. I kept it to myself unless specifically asked.
Humans are meant to eat meat, when you don't eat meat, and don't even consume decent substitutes like dairy and eggs, you tend to become very aggressive. There's a primal instinct telling you that it's time to go out to hunt, because you need meat. But because vegans have a mental block that prevents them from meeting their nutritional needs, they channel that aggression towards other humans. I suspect deep down, plenty of militant vegans would actually like to become serial killers and cannibals/vampires if given the right circumstances.
One example, he's one of the most honest ones, but I believe there are plenty of others who feel the same way, they just don't express it in public like him. (there are about 300 thousand people subscribed to his channel, a similar number to other popular militant vegan youtube channels)
https://www.youtube.com/watch?v=OR9jIVKSJ4k