Why are some socialist and communist sympathizers so arrogant and close minded?

When I try to talk sense to my older brother he's so indoctrinated and hard core liberal/socialist that he is completely oblivious to the life in a communist or socialist country. All he sees and hears is nothing but good things about communism and the social left wing policies that lead to. communism. He is like blind when I try to explain things about conservative ideals. Its like if its a liberal or communist country does something wrong he's completely oblivious and does not see anything wrong with the government.

Whats wrong with him?

Why are some socialist and communist sympathizers so arrogant and close minded?
Post Opinion