This happens when intellectuals who are sympathic to communism, fail to write and talk about the reality of the past. People - as in the masses - often go with the emotions of the loudest slogans and most prevalent propaganda. Look at South America...
Our own country is filled with people who sat by cheering on Clinton as he loved up Castro. We have millions who love communism and millions more who don't know any better.
Our intellectuals and many business leaders are sympathic to communism and have failed to document and teach the reality of communism. They have also avoided teaching America's founding ideology.
The Black Book of Communism
The introduction, by editor Stéphane Courtois, maintains that "...Communist regimes...turned mass crime into a full-blown system of government". Using unofficial estimates he cites a death toll which totalling 94 million.
The breakdown of the number of deaths given in the Black Book is as follows: 20 million in the Soviet Union, 65 million in the People's Republic of China, 1 million in Vietnam, 2 million in North Korea, 2 million in Cambodia, 1 million in the Communist states of Eastern Europe, 150,000 in Latin America, 1.7 million in Africa, 1.5 million in Afghanistan and 10,000 deaths "resulting from actions of the international Communist movement and Communist parties not in power"
A more detailed catalog (from the introduction) of some of the crimes described in the book includes:
Soviet Union: executions of hostages, prisoners, rebellious workers and peasants from 1918 to 1922; the famine of 1922; the deportation of the Don Cossacks in 1920; the use of the Gulag system in the period between 1918 and 1930; the Great Purge; the deportation of kulaks from 1930 to 1932; the deaths of 4 million Ukrainians and 2 million others during the famine of 1932 and 1933; the deportations of Poles, Ukrainians, Balts, Moldavans and Bessarabians from 1939 to 1941 and from 1944 to 1945; the deportation of the Volga Germans in 1941; the deportation of the Crimean Tatars on 18 May 1944; the deportation of the Chechens in 1944; the deportation of the Ingush in 1944.
Cambodia: deportation and extermination of the urban population of Cambodia.
China: the destruction of Tibetan culture.
The book, among other sources, used material from the (then) recently opened KGB files and other Soviet archives.