It's hard to put a number on the amount of time wasted on studying subjects which are frankly useless and corrupting. To be sure, there's always the benefit of learning from experience; but in regards to academic subjects, our time is limited with many of us having busy lives so it's vital that we focus on information that is based in plain reality.
Hayek noted that 20th century was the century of "scientific mysticism", meaning thinkers, scientists, and other researchers were grappling with ideas surrounding human affairs with no inherent grounding in anything truly objective like the physical sciences.
There is one subject which comes to mind, though I'm sure there are many others that are mostly if not completely untrue that people believe in. Sociology, the so-called scientific study of society and its behavior, was a term coined by Comte a blatant collectivist who believed in the idea of social physics; a concept that viewed social units as manipulatable like splitting atoms, in this case for the sake of alleged social progress. Mr. Comte's main point was that individuals are nothing more than raw material to be organized in select groupings and then were to be organized achieving the right efficiency depending on the values of a given society. The question that was begging to be asked, not even mentioning who would be the one to determine what are the actual values, is how can anybody even know what groups are to be considered valid for this human "technological" advancement?
The reason science has always been distinct from human affairs was the idea that subjectivity was a given in human nature, although there were the few zealous predecessors since antiquity who thought they should've been connected. No matter what any authority has thought about the right way of doing things, some individual(s) would dissent and find themselves out of step with the social engineers, this was clearly understood by the ruling class.
Of course this has and still drives the controllers mad and disgusted at the mere thought of a dissenter; because in their minds, if only people would get in line the good intentions they plan out would all come to fruition. The academic discipline of sociology is dependent on the masses thinking something or someone can control, plan, and outline social actions, but no such thing is possible. At least not in the long run, but preying on naïveté of man has short-term rewards so this course of action will continue until we come to terms with our true selves as individuals.