why do we observe initial public offering underpricing in the market? ( Use the reason of unclear on public demand to elaborate, with example support, about 400 words)

Reference:

UNCLEAR ON PUBLIC DEMAND: If the company and the underwriters do not have a clear idea about the demand for the stock, then they go with IPO underpricing. This is the best option given the circumstances. If they price it lower and there is more demand, the stock will anyway rise to its fair value, rewarding both investors and the management. On the other hand, if the management is unclear about the demand, yet they price it at its fair value, it may result in the stock price falling on the first trading day. This could force many to tag the IPO as a failure.