Um no that wasn't the reason! If that was the reason then anytime a country invaded anothter country the victory would be the invaded. Tell that to Georgia! Tell that to all the countries the Arab Caliphates invaded, the Middle East used to be a collection of different peoples, Egypt and North Africa used to be made of Black skinned Africans. The Arab Caliphates of the 7th-10th centuries unjustly invaded the entire Middle East and North Africa displacing all the inhabitants and transposing them with Arabs. Almost happened to Europe, if the Franks didn't kick their Arab behinds in. The Arab Egyptian is different than the Egyptian of King Tuts time.
The USSR won because Germany had to take on Britian, US and USSR on a 2-3 front war. Not to mention the USSR had a nice military infrastructure, many factories to produce weapons of war, a vast countryside, large population and ruthless commanders.
The USSR didn't defeat Nazi Germany on their own. No even close. If it was Nazi Germany vs the USSR in a one on one match, the USSR would have been defeated. The only country at the time that could have defeated Nazi Germany one on one was America!