The substance of financial crises. Not to mention Quantum Mechanics and Calculus. Really, there’s virtually nothing that most people do understand. Have you met most people? They’re kind of dim.
But seriously, the thing that has been striking me lately is how often zero-sum thinking is applied to non-zero-sum games. Put simply, people often believe they are in a situation in which every gain by someone else corresponds to a loss for them, when that is often not the case. Manipulation to convince people otherwise is in full swing. People are being led to believe they have to worry if others are complimented or are doing well because it reflects poorly on them, when — in fact — it does not (necessarily.)
Tiger Riding for Beginners 