>Individuals who went to great schools, emigrated and excelled in the West. They may have gone to better schools, with better teachers, or had parents who cared more etc.

In my personal experience, it's much less related to circumstantial opportunities. The ladder was derived from Germany (the model country for engineering and science) and more or less worked in practice. Of course you had better chances if you had right relatives or friends or simply happened to live near a famous school, but all my extended family and most of my circles early on in my life were Soviet engineers and scientists, and about half of them were from the absolute middle of nowhere. For example my uncle and dad were born in tiny villages that never changed since the 19th century, and still graduated from top universities as a physicist and biochemist, simply because they got noticed for their results and worked their way through. If you look at top Soviet scientists, a lot of them were like this.

However the downside of that system was that talents were filtered extremely early on, and you had no second chances to change the course of your life. You had exactly one opportunity in life to become someone, and you were forever stuck with your "choice" made at the age of 14-16 the latest. I'm glad I was lucky enough to grow up after the crash. It still works this way in many countries, actually.