Renowned historian Stephen Kotkin speculates in a recent article about what led to the collapse of the Soviet Union.
And he reaches the same conclusion as the Chinese authorities, which I recently quoted from one of their books (even before that they were busy with the causes of the collapse of the Soviet Union and learning lessons so that this would not happen in China).
"Communist regimes can liberalize the economy and survive if they do not implement political reforms at the same time, as the Soviet Union did in the 1920s, Deng Xiaoping in the 1980s, and as Xi Jinping well understands."
Simply put, economic reforms alone are sufficient for sustainability, without political reforms - as was the case with the NEP in the 1920s of the Soviet Union, and why this period and Lenin's wisdom in establishing market socialism are still praised by Chinese officials. And why the NEP is still a role model for China.
And all the other arguments of opponents, because of which the Soviet Union fell - the arms race, Afghanistan, etc. Kotkin finds them intolerable. For example, the war in Afghanistan was like bullets to an elephant for the Soviet Union. Kotkin writes:
"Afghanistan presents another misleading explanation. While America at its peak stationed 550,000 troops in Vietnam, the Soviet Union never concentrated more than 120,000 troops in a country nearly 4 times the size of South Vietnam. The budgetary cost of a ten-year campaign in the war in Afghanistan was equal to the subsidies of one year of the Afghan military campaign in Afghanistan, than the Soviet military armies. Suicide and obfuscation of public disclosures of the campaign's failures only occurred thanks to Gorbachev's glasnost. The Soviet military-industrial complex was accused of imposing an unsustainable burden on the state, but the civilian sector was much more wasteful, and a significant part of the military complex's production consisted of consumer goods."