Maybe the Russians already had it in them and we're just being held back by bad government? You don't just grow a science community in a generation you either (a) steal it (e.g. From Germany) or (b) nurture it over a long time, and the USSR was able to have both. Russia just didn't go from people running around in loin clothes to sending robots into space after the Bolshevik Revolution. There is already a deep scientific culture their before.

China even more so. For much of history, China has been the richest country on earth! Not just total, but even per capita! Ya, the late Qing and republic eras were a mess, but that China would prosper after a period of decline has happened before and isn't surprising. Mao's Great Leap Forward and cultural revolution probably hurt more than helped, and China is mostly where it is today inspite of the communists. It's all about the people.

Germany and Japan were both developed before they were devestated, and knew collectively how to develop again; it wasn't a miracle in any case. Leading countries tend to lead even when knocked back with setbacks. What is perhaps a miracle was Germany breaking away from its Holy Roman Empire roots in the first place, or Japan modernizing in the mid 19th century (incidentally, this happened at the same time). Once you make that "step", you are likely not to fall backwards.