But seriously, why didn't communism triumph in the 20th century when things were looking so good? If the russian revolution and chinese revolution can succeed, liberating 800 million people, 1/3rd of the world's population, defeat the nazis, why couldnt we finish the final stretch? What was the fatal flaw?
Also Trotsky ended up being right in a roundabout way. Once Khrushchev took over there was a decided move toward bureaucratization and this basically became baked in under Brezhnev. At that point the stagnation aging and decline of the party was set in.
This strikes me as a failure of party education and party discipline. Something the Chinese seem to be VERY strong about, presumably as a reaction to seeing exactly how the Soviets declined.
It was the decline of the ideology within the party that ultimately did them in. Destalinisation ended the soviet union.