Liberalism, carrying traits of solipsism, works well in a closed society with like minded individuals - many liberals live in closed systems, without fierce competition or compassion, so they experience their worldview as right and ignore unwanted "influences".
Opportunism is another angle where the "liberal" is the eternal "truther" keen on destroying polar opponents.
Funnily it's the mentality of many 3rd world foreigners and minorities, majority prospects, that will ultimately kill liberalism when critical mass is reached.
During revolutions, mainly well situated, liberals are often seen decorating lamp poles.
p.s.: one of the root problems of western societies lies in their adoption of a worldview incorporating elements of Hinduism