A certain section of Liberals have weak and frightened personalities that keep them from directing their anger at people on "their team" who have actual power. The thought that the Democratic party deserves it when it loses is too unmooring for them to handle, and leaves them feeling too vulnerable, so they have to protect themselves from that feeling by turning their anger on the people who supposedly betrayed the party.

Weak people have a hard time turning their anger against people they believe to be stronger than them; much easier to get angry at the relatively powerless.