USSR has a different stages. One of stages where was burst growth in almost all the aspects - medicine, science, military and economics - was when Stalin was rule. Lenin was a dumb ruler that stealing food from poor people and he is make people poor starting inner war. After Stalins death USSR have some inertia, not so dumb ruler like Khrushchev and vibe of scientists country that have a flight into the space and so on that now sometimes shows in games or other media when it wants to show strong country. But then USSR with dumbest Brezhnev was finally tasted crude oil selling and thats was needed for its elites to live rich. With the outer long wars like Afganistan its become a break point from where the USSR doesn't solve his problems but silenced and accumulated them before the end. (in 80th USSR start money printing to prolong its death, but there was too late)