[UKönig]

Germany had several problems in the way of victory, none the least of which was that hitler had no idea how to run an effective campaign. He surrounded himself with "yes men" and refused to listen to anyone who said discouraging news (could get you fired from your post or shot, in fact).
He turned his attention to Russia because he was getting nowhere with England and everyone knew it.
But the biggest problem was the supply situation. At no time were the allies less than 2:1 against, and at their high point were close to 4:1 against. By 1943 Germany was forced to run faster and faster, just to stay in the same place.
Maybe if the nazis had exploited the economies of the conquered territories more efficiently would they have had a better chance.
They were the first to develop and deploy jet turbine engines for the Me-262 and the Ar-234, but after their early victories, in Poland and France, these technologies got pushed back. Mostly because they assumed the war would be over shortly so there would be no need to develop jet aircraft. By the time they realized their shortcomings, it was too little, too late. The advance U-boat program suffered exactly the same thing as the jet fighter program, namely, quality of materials and workmanship was at an all time low.
Also, hitler had this attitude of competition rather that co-operation amongst his underlings, so instead of working together in getting things done, they all fought against and undermined each other with petty power politics.
No, what happened, happened for a reason and I am grateful for the allies and their efforts. I learned German today not because I had to, but because I *wanted* to.