> The USSR didn't even make it to its 70th birthday.

Not because the will or the struggle of the people.

Gorbachev began to abolish the aforementioned totalitarian measures, creating the opportunity for a party coup. If totalitarian control had not been weakened, nothing would have prevented the Soviet Union from existing to this day.

> Gorbachev essentially destroyed the USSR

No, he didn't do that. He loosened the totalitarian control, and that was it. Then other opportunistic leaders of the Communist Party took advantage of the situation and seized power, dividing up the resources of the huge country among themselves. And because the old regime was full of shit and everyone knew it, no one stood up for it.

> his actions are almost certainly a key reason that it no longer exists today.

Rather, his actions were the reason why the Soviet regime lasted so long. I mean, the unviability of the socialist project was a proven fact in 1918, long before the USSR was even called that. And everything that happened after that was simply an attempt to cling to power by totalitarian and terrorist methods, first by Lenin, then by Stalin.