The hatred against/stereotypical vegan was made by beef lobbies to sell more meat
Compared to vegetables/grain, meat(especially beef) is a lot harder to produce/less sustainable; you have to take care of livestock for multiple years, you have to have a proper butchery, you have to deal with processing tons and tons of waste, and so on.
But in America, cows are a staple of diet: steaks and hamburgers are considered an American delicacy, despite the fact neither really had its origin in America. Compare that to other countries: their staple diet is far less concerned with beef, and lot more with grain and vegetables, or more sustainable meats like chicken.
So, in order to maximize profits, beef lobbies/companies have influenced American culture to associate themselves with beef: those who eat beef are strong, intelligent, capable individuals who are caring, while vegans are raging critics who hate everything, but still secretly like beef.