None of the vegans I know in real life are as hostile as some vegans get online. Probably a majority of vegans I see online (or in interviews, articles, etc.) aren’t hostile. The hostility is coming mostly from vegans who think it’s a useful tactic to get others to agree with them.

It’s a whole other discussion about how effective that tactic is, or who it’s effective on. But it is definitely a choice, because there are tons of vegans out there who choose to present their ideas differently.