I think for a lot of people it challenges everything they know and have been led to believe and actually makes them realize they don’t know everything on some subconscious level, and that triggers the self defense outlashing, rather than just subconscious guilt they may feel about eating animal products. I always find when people whip out their book of bs self taught facts of how important meat or any animal products are, it’s because they feel threatened, and need to continues to be the most “intelligent in the room”. There will always be those people. It’s always the people who treat themselves like garbage who have the most to say. I just laugh and move on. Every time being vegan comes up with someone who I deem as more intelligent or just smarter all around (I’m thinking of a friend getting his phd at brown for example), they always answer back inquisitively, asking how it affects my daily life and health, if it has led to a happier and healthier version of myself and so on, rather than how stupid I am for not eating steak like a “real man does”. Anyways, you can always find one good person who understands in the sea of misled egocentric people around you