The concept of value is a fuzzy one, and valuation is often more art than it is science. Psychology has always played a role in money and investing — and there have always been bubbles, too, where the price of an asset takes off at a rapid pace and disconnects from the fundamental value. As Jacob Goldstein wrote in Money: The True Story of a Made-Up Thing, all money is sort of a collective myth. “Money feels cold and mathematical and outside the realm of fuzzy human relationships. It isn’t,” he wrote. “Money is a made-up thing, a shared fiction. Money is fundamentally, unalterably social.”