I still didn't read the above though, so I am not sure of its quality.
I think Hitler's biggest mistake is that he didn't understand that his country was being setup for destruction, I believe he had some dealings with the British aristocracy before the war and they double crossed him. I think he only realized it after the Russian campaign. Also Mussolini really ruined things.
https://www.pdfdrive.com/how-hitler-could-have-won-world-war-ii-the-fatal-errors-that-led-to-nazi-defeat-e164795303.html
I still didn't read the above though, so I am not sure of its quality.
I think Hitler's biggest mistake is that he didn't understand that his country was being setup for destruction, I believe he had some dealings with the British aristocracy before the war and they double crossed him. I think he only realized it after the Russian campaign. Also Mussolini really ruined things.