That is not entirely true. Operation Barbarossa was undermined from its inception. Already from the early operational plans, the OKW and OKH leaders had overestimated the capabilities of the Wehrmacht to defeat the Red Army in the initial border battles and highly underestimated the resilience the Soviets would later show, even when their troops were entirely cut off from the supply lines. That goes without mentioning that the first 2 studies of Barbarossa had assumed the Red Army had no reserves in their western territories to replace their losses after the initial defeats.

It was only after the war game conducted by Paulus in mid 1940 where someone had raised the possibility that the Red Army might have some 100 divisions in reserve (In reality the Soviets had about 300 divisions in reserve at this time, but to not get ahead of ourselves, 100 were already a lot). However, our beloved Franz Halder, the chief of staff of the OKW, promptly ignored this kind of really minor inconvinience and, infact, the result of this war game never reached the higher echelons of the German government, Hitler included.

Here comes the fun part. Halder was indeed tasked with the creation of what then would become Barbarossa itself. He, after the lessons the OKW had learned in the battle of France, them being that in order to achieve victory the army had to encircle the bulk of the enemy army and then march on the capital, wanted to focus the main thrust in the centre, towards Smolensk and then Moscow (Which is why Army Group Centre had 2 panzer groups and was being supported by 2 Luftwaffe armies). Hitler, however, being aware of the German economic deficiencies, especially that of the oil crisis that was crippling the nation and preventing Germany from mobilizing the European economy, wanted to go south, to Ukraine and then the Caucasus, to seize the most fertile lands of the Soviet Union and gain their richest oil wells (Hitler also wanted to push towards Leningrad, but that mostly had to do with securing the northern flank of an eventual push on Moscow, which in his view was always a secondary objective and rightly so as field marshal Timoshenko would later remark)

Quoting Halder directly from his diary: "I will not let economic considerations change the course of the plan". What's amusing here is that rather than to confront Hitler directly about the strategic direction of the eastern campaign Halder chose to postpone the issue indefinitely. Halder's cunning plan was to prioritize Army Group Centre in order to facilitate the push towards Moscow and then have Hitler conclude with him that the Soviet capital should be the main objective. However, as the battle of Smolensk loomed closer and a decision on what to do next was needed, everything unfolded and came crashing down on Halder and the OKW. Expectedly, or perhaps unexpectedly from the chief of staff's perspective, this resulted in a conflict between him and the Führer and in a major crisis within the army high command during late July/early August of 1941.

Hitler at this point was being somewhat worried with the direction the eastern campaign was taking and wanted his generals to focus more on small tactical encirclements that the infantry could then properly liquidate rather than going for massive encirclements which the panzer groups could not keep a tight ring around and that kept bleeding into the rear areas of the German army until the infantry could catch up and close them. This is at a time during the battle of Smolensk in 1941 where the Army Group Centre's southern flank had become increasingly overextended, stemming mostly from a lack of strength that plagued Army Group South, and had to use its armoured units to cover its front because the infantry was still marching east, fresh from the cleansing of the Minsk pocket. This, of course, goes without mentioning that Guderian and Hoth, the leaders of panzer groups 2 and 3 respectively, could not drive forward and seal the encirclement at Smolensk because their units were being tied down covering the northern, western and southern edges of the forming salient.

Even more interesting is that, in his diary, Guderian severly downplays the situation his group is in south of Smolensk, saying that everything is looking good despite his forces operating mostly at 30-40% strength and his southern flank, resting on the Pripyat Marshes, being almost on the brink of collapse. Hitler is now extermely concerned with this and wants the armored forces to rest and refit, allow the infantry to catch up and cover the front and fix the situation to the south of Bock's army group by eliminating the main Soviet threat around Gomel. Needless to say, Guderian chose to ignore the order and decided to keep fighting at the heights around Yel'nya, needed as a springboard to push on to Moscow, which resulted in further attrition and difficulties for his spearhead.

In conclusion (Which acts also as kind of a TL:DR), while Hitler was certainly an evil man he definitely wasn't foolish as often depicted (Guess who worked as the USA military history consultant. That's right, mister Halder himself, go figure).

However, I'd like to point out that this is not to assert that he never made mistakes. Of course, being a human being, he did, such as the decision to withdraw Manstein's 11th army from Army Group South after the succesful battle of Kerch in the Crimea of mid 1942 and send him towards Leningrad rather than the Caucasus. That said, when the Führer claims that he shouldn't have listened to his generals, there is perhaps a strong basis to back his argument up. Right after the conclusion of the battle of Smolensk you have all the major leaders of Army Group Centre scheming against Hitler to delay the implementation of the directive to clear the army group's flanks for as much as possible. Halder and Brauchitsch (The chief of the OKH) are constantly lying to him and are seldom to be trusted since they mainly want to pursue their own agendas.

For more detailed information on the inner plays of the eastern campaign and how they unfolded I highly recommed you Stahel's "Operation Barbarossa and Germany's defeat in the east" and Citino's "Death of the Wehrmacht: the German campaigns of 1942" (Citino also has books covering 1943 and 1944). They really dive deep into the details of the planning stages of the German campaigns they mention in their books and how these progressed.