Interesting point.....not too often made.
It seems to me, after almost six decades as a voting-age adult and having been exposed to the theories, strategies, and tactics of Marx and all the subsequent deriviatives thereof, that the main purpose has always been the control of the mind, property, and souls of those they rule.
On this basis a case could be made that Marxism, Fabianism, Socialism, Nazism, Communism, Gramsci_ism, and a few others have always succeeded.
"Failure" is a legitimate attribute only if other sordid undesirable (from their point of view) attributes such as "freedom", "prosperity", "liberty", and "happiness" have to be included in the analysis.
Classical Athens lasted about 170 years. This may be all that we can do as Americans before sinking into the mire of typical governmental tyranny that most of the world has faced since the Sumerians built their first city.
In a thousand years, someone might emerge with the Federalist Papers and the Constitution and wonder about us and examine what went wrong.