Germany simply could not compete with the awesome might of the Allied Powers. Germany could also not rely on it's allies to help with the war effort. Whereas the Japanese had an awesome navy, they lacked in everything else. The Italians lacked in resilience, and the Baltic states made little headway.
On the Contrary, Britian and the Commonwealth could hold on their own, even managing to launch offensives. The U.S. and U.S.S.R both had an enourmus manpower pool and huge industrial bases. The Allies had Air and Naval superiority, which only further sealed the Reich's fate.
Simply put the Germans albeit they had Tech superiority could never manage to fight on numerous fights and sustain the casualties they later on sustained. Especially since most of their allies were grossly incompetent (besides the Finns).
In the end they were simply outproduced, outflanked and outgunned. Nevermind the complete ideotic tendencies of the Fuhrer and some of members of the O.K.
As Admiral Canaris once said, "All we need to do is follow orders and this war will soon be over".
