The Cold War sowed the seeds of this self-immolation long ago. By casting the conflict between the superpowers as an ideological showdown, both the United States and CCCP began to define themselves in terms of opposition to a strawman idea of what they thought the enemy was. E.g. America was a country with a strong unionist movement, but quickly turned on itself with Communist witch-hunts and distrust of centralised planning (it didn’t help that the security apparatus of each power were genuinely infiltrating grassroots movements in the other.)

Obviously the Soviet Union was first to fall, but the poison was already in the blood by then.