The Theory of Height of Incompetence

There exists a theory of Height of Competence and Height of Incompetence. It summarily states that every person rises to the height of incompetence at the same time he rises to the height of competence. The clichéd example is that of Adolph Hitler. Hitler rose to one of the biggest demagogues of all time . Evil perhaps , but a great demagogue nevertheless. His ability to hold the mass almost bordered on mass hypnosis. Many a social scientist has earned his keep by analysing the effect of Hitler on the masses and convince them to ignore ,abet and even actively participate in mass genocide. In fact one of them coined a term "banality of murder" for the phenomenon. He galvanized a nation abjectly humiliated in WW1 into action and literally shook the core of the world order. And then he went on to rise to his height of incompetence as a military general/strategist. Against all sane advise he opened two war fronts at the same time (Britain and Russia). He met his Waterloo (ironic choice of word) in the unforgiving biting cold of Russia and thence hence the downfall. Incidentally a couple of centuries before that Napoleon Bonaparte attacked Russia in the peak of winter and effectively killed his expansionist plans. To wit, people who forget history are condemned to repeat it. So the height of incompetence can actually fritter away all the gains that the heights of competence that is accrued. Let me give another example albeit a muted one though. Sachin Tendulkar rose to his level of competence as a batsman but rose to his level of incompetence as a Captain. So much so he relinquished the captaincy and never took it even when it was offered on a platter.
So what is it that makes this dichotomy so antagonistic to each other. I have a theory to rationalize it though it has no basis in either empirical observation or academic research.
And there is one word to describe it. Hubris. Since one gains mastery of a certain domain , one assumes that the same success can be achieved in another domain. It might stem from sheer arrogance (which might be true in the case of Adolph baby) or it could be that the new scenario throws one off so badly that the skill toolkit acquired in the area of expertise is not relevant to the new domain (in case of Tendulkar, perhaps). But does it mean one does not use a skill set on one domain in another. I am not advocating that for one second. In fact may a breakthrough has been achieved through cross pollination. A classic example being the encryption techniques used for torpedo guiding in WW2 being adopted by musicians from orchestra experience. I am suggesting a little humility to the craft required for the other domain and the ability to listen. Success is a function of several parameters and some of them are specific to the task at hand. It means there is no free pass to success. It is equally important to understand one's strengths as well as weaknesses to get one's objectives. It is equally important to listen (and not hear) experts and internalize their ideas. I am not in favour of abdicating responsibility to the experts. As a leader, the buck stops with you and it is your responsibility to take that call. But it also does not mean you force the experts to abdicate their responsibility to you. And the core of it lies in the dictum "The monopoly of expertise does not reside with a single person"