There are very real people who have been harmed by side effects from the vaccine.

Whether the virus itself would've been more deadly is a question for another time, but if your loved ones were unlucky enough to get myocarditis from the vaccine, and you were silenced on social media, sometimes invisibly like you're being gaslit, and so were the doctors and researchers, it's easier to understand the strong emotional reactions to unnamed large entities colluding with other large consumer facing entities.

This also creates a tendency to migrate to communities that share your point of view, creating an echo chamber.