To grossly oversimplify things, there are two kinds of vegans…

Type 1 are “healthy living” and “sustainability” vegans. These type are generally benign, polite, helpful, and keep to themselves unless asked. They also tend to not be super militant about their veganism… like the occassional egg from someone’s beloved home-raised chickens is fine.

Type 2 are ideological vegans. These types believe that “exploiting” “living creatures” in any way is fundamentally immoral, and because it’s a morality issue (e.g. basically religion) the vast majority are very preachy, demanding, and in-your-face about it. They don’t consider type 1 to be “real vegans”.

Type 2, being the loudest and most abrasive, giving veganism a bad name and ruining it for everyone.