Left Destroys

Somebody commented days ago on Facebook that they were shocked that, while the right seeks to defeat the left in politics, the left seeks to destroy the right.  Why?  It's been that way since the beginning.  That's how it was in The French Revolution, when the left destroyed the property of the Church, aristocracy, establishment, private property, and murdered leaders, administrators, and clergy.  It was that way in The Communist Revolution in 1917 when the left banned religion, killed the royal family of Russia, and confiscated all property from the people of Russia.  Even in Germany, the National Socialists party took power and outlawed all other political parties.  So, why should the left change now.