They have a need to justify their warped worldview. They believe we're evil authoritarians, and they are taught to hate authority (unless it aligns with their wants), and so they will harass and argue with us in bad faith until they are inevitably banned, all so they can say "See? They silence those they disagree with!" They have a martyr complex and think harassing people online by talking out of their ass is like standing up to tyranny. It helps them deal with the dissonance of believing they're free and righteous while supporting the most warmongering regime in human history.