People, countries and ideas are destroyed through their inability to resolve their contradictions. The left gained a foothold in America by exploiting the country's contradiction between its insistence on moral superiority and the actual way that the sausage got made. The left did not resolve this contradiction, instead it pretended that it had transcended the contradiction because when it made the sausage and broke the omelets, it was doing it for the greater good.
Under the old system, human misery was caused by the pragmatic problems of reality. Under the new system, it was caused by the idealistic necessities of the greater good.
For example, before ObamaCare someone who couldn't get health insurance was suffering for pragmatic reasons. With the advent of ObamaCare, someone losing their doctors and getting stuck with insurance they couldn't afford was suffering for the idealism of the greater good.
The contradiction between the aspirations of the ideal and the brutal necessities of the real were not resolved. Instead the left made the suffering of individuals and groups irrelevant.
The left expanded its collective representation beyond the individual and even the nation. It enclosed the entire world and immunized itself against any moral challenge. By representing the welfare of the entire human race, any suffering it inflicted short of that could be justified for the sake of a majority.
Eventually the left was also destroyed by its contradictions, the dream died leaving behind gulags and ghettos. Nothing had actually been fixed. And the left insisted that it was the impulse of the ideal that was noble, regardless of how badly it was managed. As it had all along, it chose to die on the ideal, rather than live with the real.