Unless there is a crushing unbalance of powers, a war is not 100% won or lost when it starts.
Counting the gaiter buttons is not the right way to predict who is going to win the war.
Because on the paper, Alexander the Great should never have conquered the Persian empire, Caesar should have never have defeated Pompey and the optimates, Edward III and Henry V should never have inflicted crushing defeats on the French, Napoleon should never have lost the Russian campaign, ... etc. And however it happened, contrary to the odds.
The French government launched a propaganda campaign, in the beginning of WW2, whose caption was « we will win because we are the strongest », with a world map showing the extent of the French and British empires.
With hindsight, we know that given Germany’s edge in military doctrine, Britain and France alone could not defeat Germany and France was knocked out of the war in 6 weeks.
Most often, the one who wins a not too unbalanced war is the one who sets rational goals and is able to execute the right strategy.
Setting wrong goals or giving right goals up to suddenly follow nonsensical goals always is fatal.
I don’t mean Nazi Germany was doomed from the start in 1939. This is not the right POD.
What I mean is that Nazi Germany was doomed from the start in 1933 and even in 1924, in the sense that Hitler’s and the Nazis goal was suicidal. Waging war against the USSR to conquer a lebensraum for Germany was suicidal because it was obvious it would end in a 2 fronts war. It also should have been obvious that the USSR was too big a piece to swallow for Germany.
But if Hitler had been more rational, would he have been Hitler ?
Being rational would have implied giving-up the goal of conquering the eastern lebensraum and remaining in friendly terms with Stalin until Germany could force the UK and the US to accept German domination of central and western continental Europe.
And Hitler had no such patience.