The narrative I've heard was that Hitler continually defied the competent advice of his capable military leadership and for irrational reasons diverted the Moscow army group south, losing the military's momentum for a far less strategically important objective. In short, I've always heard about Hitler's irrational strategic decision making. Attacking the Soviets when he did was another; "Hitler shouldn't have opened a second front. That was irrational etc".
The decision to attack the USSR (by that time, the fair and responsible trade partner which was already supplying Germany with resources) was fully rational, in its own way. Hitler just did not take Russia seriously and hoped for a quick and relatively easy victory that would allow him to turn against the "main" enemy.
He's not the first who made such a fatal mistake. In early XVIII century, Swedish king Charles XII, being already at war with Russia, after the very first successful battle with "Muscovite hordes" distracted to "real" and "stronger" enemies like Poland and Saxony. And just one decade later Swedish greatness and ambitions were fully destroyed (not by Poles or Saxonians, of course). But this Charles XII wasn't the champion strategist, there were even more brilliant plans:
Operation Pike was the code-name for a strategic bombing plan, overseen by Air Commodore John Slessor, against the Soviet Union by the Anglo-French alliance... The plan was designed to destroy the Soviet oil industry, to cause the collapse of the Soviet economy and deprive Nazi Germany of Soviet resources.
Planners identified the dependence by Nazi Germany on oil imports from the Soviet Union as a vulnerability that could be exploited. Despite initial opposition by some politicians, the French Government ordered General Maurice Gamelin to commence a "plan of possible intervention with the view of destroying Russian oil exploitation"
Do you see? This is the same logic of Charles XII: war against USSR is a less significant factor than chance to "weaken" Germany. And these suicidal plans were already on the way to real implementation:
As of 1 April, four squadrons comprising 48 Bristol Blenheim Mk IV bombers were transferred to the Middle East Command, supplemented with a number of single-engined Wellesley bombers for night missions. A French force of 65 Martin Maryland bombers and a supplementary force of 24 Farman F.222 heavy bombers were allocated for night operations during the campaign. The French were preparing new air fields in Syria which were expected to be ready by 15 May. The campaign was expected to last three months and over 1,000 short tons (910 t) of bombs were allocated to the operation.
It was only the German blitzkrieg in France that sent this plan to the trashbasket of history. Otherwise, the whole course of WW2 would be very different from what we know today: after the very first Anglo-French attack, USSR would enter the war on German side. And few months (or years) later, sitting in German (or Soviet) concentration camp, those British and French strategists would have enough time to curse themselves for what they did...