IF, IF, IF... If wishes were fishes, we'd all cast nets. I do not know what alternate dimension Grab came from but his WWII doesn't resemble the WWII I learned of. Chief of Chaos has it right. Germany's biggest flaw was Hitler. He eventually would have defeated himself regardless. Mental illness never gets better on it's own, only worse.

Brittan may have held out for quite a while but she was doomed without interventions from the US and Russia. IF Hitler had taken the time to consolidate his advances. IF, he had taken time to lie to the rest of the world and "made nice" while repairing, improving and developing his war machine. IF, IF, IF. Hitler had what would have been the greatest pincer attack in all of history if he could have waited and co-ordinated with Japan against Russia. IF.

Then there are the Japanese "IF's". If Japan had waited but a little longer to attack Pearl. Or if she would have followed up on Pearl and gone for the mainland and at least have set back our ability to respond until Russia had been dealt with. If!

The U-boats weren't trumped by GB. Any urgency that was placed upon Germany was done so by the threat of US entry into the conflict.

One of the key factors that lead Germany to war in the first place was limited access to the oceanic trade routes. German found economic competition particularly tough on the international scene. She needed more ports under her control prior to the war.

Too many IF's. It is too hard to point to a single factor, even Hitler himself. Germany's plight was profound and you could argue that the situation created Hitler (a Hitler). IF.