GDP is a terrible measure of anything, except for monetary policy... which is almost entirely irrelevant to any kind of sociological considerations. And your h

GDP is a terrible measure of anything, except for monetary policy... which is almost entirely irrelevant to any kind of sociological considerations. And your history is inaccurate. The primary consideration is simply that they were starting from a much lower base. They were an agricultural peasant society, with a fertility rate of over 5 children per mother. The USSR was growing at breakneck pace during the first half of their existence, but just in very particular sorts of ways, as a result of forced collectivization, forced urbanization, and forced industrialization. However, they levelled off quickly during the postwar years, even though they had a strong focus on nuclear research, space exploration, etc. They had no one-child policy, they simply underwent a sped up version of the normal Demographic Transition, and ended up with below-replacement fertility rates just like Japan and many others have. This, in combination with poor central planning, and no more low-hanging fruit, led to their stagnation. With war, and a glorious leader, uniting the people to undergo a complete transformation of their entire lifestyle, the rate of growth can be astounding. But in the postwar years with absolutely none of that, and an already-industrialized economy, you run into a sort of nihilism, and all your lies become less likely to believed, and production targets less likely to be strived for. (see: optimum tautness) Also the complexity of modern life, aside from the basics that they achieved early, is just very hard to plan for. Think of all the millions of niche products that you can buy, and then imagine trying to dictate to an entire economy how to produce all of that.