I think it's desperation.

They have an irrational fear of being nuked by Iran, they know any peace will have Iran secretly making nukes (which is easier every year), so they lash out to prevent that even though it's self-destructive behavior; the modern Left would nuke Israel themselves if they could, and Right support is waning.

It's so obviously a bad idea to turn their last bastion of support against them, but they're not thinking rationally.