Under Khrushchev, revisionist elements became mainstream, success became no longer an internal characteristic but one entirely dependent on the west, the west was the definition of “success” and if “couldn’t compete” with the west, then it was a failure, western culture became hegemonic over soviet one - the system rotted from the top down. And the soviet union tried to spread this view into the rest of the Warsaw Pact states.

East Germany had it worst because it was economically isolated (basically non-recognised by most states, which the soviet union never really pushed for) but not culturally, one could argue that the east german leadership survivors of the camps and purged by the nazis never really trusted most of its own populace and hoped to “wait them out” and hope for the next generation to be “better”, ironically it was the boomers & older gen x who brought down the GDR, not those who had lived under nazi rule and had various degrees of complicity. So it wasn’t 70 years of socialist institutions breaking down suddenly, but socialist institutions serving decades and decades of rot, until not even the proletarians believed socialism was going to work.