economic bubble
A phenomenon in economics in which too much loose cash finds its way into an area of the market, e.g., stocks, housing, dot-com, etc., resulting in a buying frenzy that leads to wildly inflated prices. Economic activity in those areas affected is not sustainable in the long run, so large numbers of late investors eventually go bankrupt.
We were warned of an economic bubble, but bought high-priced shares anyway thinking we could unload them on some poor sap before the bubble burst. Boy, were we wrong!