But real house prices can diverge from market fundamentals when there is widespread belief that today’s robust price increases will continue. If many buyers share this belief, purchases arising from a “fear of missing out” can drive up prices and heighten expectations of strong house-price gains.
This self-fulfilling mechanism leads to price growth that may become exponential (or explosive), resulting in the housing market becoming progressively misaligned from fundamentals until investors become cautious, policymakers intervene, the flow of money into housing dries up and a housing correction or even a bust occurs.
Expectations-driven explosive appreciation (often called exuberance) in real house prices has many consequences, including the misallocation of economic resources, distorted investment patterns, individual bankruptcies and broad macroeconomic effects on growth and employment. link