Gorby was a protege of Andropov, knew the real situation of the Soviet Economy, and realized it was on the brink of a total collapse.
Because Reagan had worked with others to lower the worldwide price of energy to levels the Soviets couldn’t compete with, the Soviets couldn’t afford to even pay for the grain they had ordered from the West, while railcars full of grain left the Central USSR, and arrived in the cities empty, due to corruption all the way up the line.
The Black Market in the USSR was bigger than the official economy, at that point.
They were on the verge of a mass starvation outbreak. Cutting the Republics loose bought them another few months.
I guess forgetting history isn’t something that just happens in America.
The USSR didn’t have to collapse. Their communist economy had to modernize and they could had pulled a Deng (Chinese economic reforms in the ‘70s)