Our brains are hard-wired to be susceptible to specific patterns. Ancestral humans who stayed in good graces with their social group, even when the leaders of that group were factually mistaken, survived at higher rates than humans whose respect for facts drove them to reject or be rejected by the group. The details of which and to what degree we have these triggers override our rationality varies by genetics and environment, but we are all susceptible.
That a very significant percent of humans respond to their system by adopting specific harmful behavior is not something we can fight by moral condemnation. Labeling them as bad people is unproductive. If the goal is to actually reduce the harmful behavior, addressing the system - not the individuals - is the only effective strategy.
Mob violence has been a thing for all of human history. Before humans, even: chimpanzee groups, if they get large, will split into two groups. After a few months apart, if the groups encounter each other, the stronger group will murder every individual in the weaker one.
I think we had settled on a regulated and normalized system in pre-internet media that moderated the mob violence tendencies. Our current polarization is not really that social media created this new thing in society, it’s that it removed the guardrails in traditional media that were suppressing natural human tendencies. I hope we can figure out and implement some new guardrails sooner rather than later.