Lately stuck on WW2 history.

[Anomalocaris]

The war between Germany of Russia was pretty much inevitable.   The longer Germany wait to invade the USSR, the weaker Germany forces involved in the invasion would be relative to soviet defending forces.

Not the point.

The more I look at the over all tactic of Hitler's Nazis, the fatal flaw in his tactic is that he more often than not thought that by expanding, you could simply take over the defeated's resources. I think the main reason Barbarossa failed, was because once he invaded, he didn't have enough supplies or time to utilize the captured territory's resources. 

The real reason for war are strategic control over resources. If you don't have enough supplies and bad planning, you might have initial success, but wont have the time to take advantage of what you capture.

The problem with exploiting resource seized from occupied land that you described is a long terms one.  It takes several month to a year to begin to make occupied resources productive in th ebest of scenarios.  Operation Barbarossa was lightning attack that started in June 1941 and had failed by dec 1941.   There was never any way Germany could have utilized occupied resources within 6 month so that it could have made the slightest difference to the outcome of operation Barbarossa itself.  

In so far as germany’s Failure to utilize occupied resources affected germany’s Ability to wage war against the USSR, that effect probably only really kicked in after 1943.   By the time Germany had already lost all chances of actually defeating the USSR.   The only impact germany’s Failure had was to make the massive soviet offensives of 1944-1945 easier and maybe brought forward germany’s Final defeat by a few month to a year.

Regarding why Barbarossa failed, although the German army did exhibit some very impressive tactical skills pulled off some bragworthy successes, on the whole, German entire high level effort from pre-attack reconnaissance, logistic planning, clarity of objective, situational appreciation, and plan for an end game was one massive clusterfuck.

In some ways, Germany and the german army has this tendency to view successful large scale offensive as an end in itself, not an means to an end.   Instead of justifying why they are trying to achieve particular success in light of a clear strategic end game, they have a tendency to look for opportunities to achieve spectacular tactical success, and then take it on faith that once great success is achieved, how that tactical success will convert to a favorable strategic outcome will just magically become clear.

So in some ways German offensive become an exercise in looking for Russian troops to kill rather than eliminating Russia’s ability to field more troops.