lol...quite...
Gross mismanagement of the entire war effort for the most part. While the allies went onto wartime production in all factories almost immediately, Germany didn't... also the Arms Production itself was badly managed - we all assume that Germany was uber-efficient at all that stuff, but any detailed look at how the Third Reich did 'business' reveals a catalogue fo hopeless ineptitude from top to bottom...
Take the V1 and V2 Rocket programme as one example...so much money and materiel was expended on that one effort that it severely curtailed aircraft and U-Boat Production - the U-Boats that Germany went to war with were actually training boats, never intended for warfare by the Kriegsmarine (source: Peter Cremer, U-Boot Kapitan-Lieutnant, Commander of U-333). The boats that they were supposed to fight with weren't ready until December 1944, by which time it was too late.
The V2 rocket, despite being technologically advanced, accounted for surprisingly few casualties - according to allied sources, the average death-toll was about 3.5 persons per rocket. According to the German Aerospace museum at Peenemunde where the rockets were developed, each rocket cost about 3 billion Reichmarks to produce, taking into account all the R&D that went into the program (and much of the construction and assembly work was by slave-labour, so costs would have been even higher in a 'real-world' scenario).
That's not a cost-effective way of killing people...
Imagine if that expenditure had been spent on the jet-engine programme instead: the prototype Me 262 jet-fighter was ready to fly in 1942; only material shortages and funding prevented it going into production at that time. The strategic metals needed for the Jumo jet-engines was in short supply, why? Because they all were allocated to the V1 and V2 programmes.
If swarms of Me 262s had been flying over Europe 6 months before the arrival of the long-range NA P-51 Mustang, we'd never have been able to maintain air superiority. Without air supremacy (as opposed to superiority) the Normany Invasion wouldn't have taken place.
With more, modern U-Boats, the Atlantic convoys couldn't have kept Britain resupplied.
Lots of what-if's - but it wan't the quality of personnel that lost the War for the Germans, it was poor long-term planning, worse management and poor understanding of how best to use the limited resources available.