When everyone online is piling on someone, staying out of it is a quiet kind of leadership.

A pile-on offers something genuinely tempting, which is belonging at no cost to yourself and considerable cost to somebody else. The crowd reads your silence as abstention while the person receiving it reads it as mercy, which makes doing nothing one of the more useful options available. There is no version of joining in that helps anybody.

When a thread turns on somebody, close it and do nothing. Do not add the mild version or the joke. If you have it in you, send that person something ordinary and unrelated, which lands better than sympathy does.