Answer:
Changes were occurring too rapidly.
Why did the Soviet Union collapse?
The Soviet Union lost all its money.
By 1991, it was unable to continue operating its massive military-industrial complex alongside its civil economy, which provides people with food and shelter. For the first time since World War II, the Kremlin had to decide.
Stalin and Lenin would have gone into the armed forces. They would have put an end to the uprising by engaging in an unprecedented bloodbath and strangling of the populace. In the 1990s, the North Korean Kim family tried it and it was successful.
Gorbachev and company were not in the mood to slaughter people. They stopped funding the military. For that, mankind awarded Gorbachev the Nobel Prize, and the whole Russian people—apart from certain trash like myself—have hated him forever.
The military-industrial complex, which makes up at least half of the economy, came to a grinding halt; entire regions shut down; troops went hungry; and the effects spread all the way to Moscow.
Then the major event that you are familiar with from history books occurred.
The USSR was an empire of communists made up of many ethnic republics. The ethnic elites didn't see any need to submit to Moscow when the funding from Moscow dried up and the terrifying Soviet apparatus of oppression and control ran out of fuel.
The fifteen republics all took different paths. The USSR experiment had come to an end.
The evolution of Soviet gold reserves during the course of Soviet rule is seen below. Gold exports and reserves, in metric tons. The gold exports seen in the red line below were mostly used to purchase food in the West.