Why? He's telling the truth. But what he means is that vast numbers of people are liberal until he or she gets punched in the face by actual reality.
It brings to mind a kindly woman I knew back in the early 1970s. She was what was known back then as a bleeding-heart-liberal and was adamantly against the death penalty until her own grandchild was murdered during a home invasion robbery. That turned her into a law and order and JUSTICE conservative right quickly.