Isn't this a tautology, though? Isn't the definition of value, "whatever people think something is worth?" It's good to be reminded that value emerges from in

Isn't this a tautology, though? Isn't the definition of value, "whatever people think something is worth?" It's good to be reminded that value emerges from individual decisions made by individual traders that collectively form a market. Still, there is also benefit in understanding whether there is some external objective reality that is influencing those decisions. Sometimes, value decisions are arbitrary or irrational—but over time, value decisions tend to be rational and based on underlying fundamentals of the thing in question, do they not? People who buy and sell things have the same mental capacity, after all, as the observers who are on the outside asking about the "fundamental" utility of the thing to which value is being assigned. Wouldn't the people who have something at stake in a transaction have more incentive to develop a theory of underlying value than would disinterested observers? If they do develop a theory of underlying value, wouldn't that theory guide their pricing decisions when buying and selling? And if so, how is the "fundamental value" of a thing distinct from the aggregated theories of value that buyers and sellers of that thing hold over its lifetime? Accurately assessing this "fundamental value" might not help you as a short-term trader, but it surely can improve the decision making of a long-term investor, no?