Suppose someone does something a minority dislike and the majority are indifferent towards. Once the minority has struck out at the person, many of majority start striking the person out of a sense of community catharsis or joyous solidarity.
What would you call this sentiment or behaviour?
For instance, I see someone post a bad answer on a (different) stack exchange. I withhold downvoting, but then one or two people down-vote and harangue the poster, at which time I and many others start downvoting in a veritable flood; with a sense of warped pleasure that that poor poster isn't us. Isn't One of Us, at least for today.