The Soviet Union was starting to stagger as early as the late 1960s, when life expectancy began to fall. It had great achievements in human and economic development, but these seem to have been a matter of seizing low-hanging fruit (an achievement, to be sure). This was linked to the general theme of post-Khrushchev stagnation: The systematic failure of the Soviet economy, second-largest in the world and with immense human resources, to innovate and escape the middle-income trap, left it surpassed first by peers then by countries once much poorer. This had implications for living standards and Soviet power.
The Soviet condition might have seen superficially stable, but it was bound to implode when there was a shock. Such a shock was going to come, whether through internal failures or external shocks. We are lucky that Kennedy's observation that declining powers need a war to trigger their implosion did not come true here.
The superficial stability came as a result of the high oil prices of the 1970s - it was clear that upon the abandonment of the Kosygin reforms, which might have if carried out fully, led to a more sustainable industrial picture, Soviet industry, with it's fixation on more and more production of capital equipment, was becoming an anchor on the state. They knew this in the late 60s. But they had no incentive to make alterations in the 70s because the inefficiency of Soviet industry was papered over by gains from the oil sector.
They could have invested those gains in improvements in industrial structure, or the development of the sprouts of a consumer economy. This was not done - there were some good investments into infrastructure but mostly it was military hardware, and a feeding frenzy for the elite.
The 80s around the world presented challenges to industrial economies everywhere, and most countries had to make painful decisions regarding expenditure and efficiency of state supported industries. But it was not a complete catastrophe everywhere - Israel and the US dealt with inflation, Britain with a sharp rise in unemployment, France with diminishing growth, Canada with a combination of the 3, etc, but the economic problems were eventually surmountable. The Soviet Union was a different story - it was so dependent on oil revenues and had an industrial structure that was so brittle that it wasn't able to find a soft landing.
That being said, the dissolution of the USSR was first and foremost a political crisis over the governing structure and only secondarily a social and economic collapse