Importance of estimating the product demand

This is a forum post. I need to answer this question; I need to post on someone else post. Why is knowing (or estimating) the product demand so crucial for a firm?

In your response, include an example of a business that has suffered from poorly estimating the demand of its products. Evaluate how or why the business made such a mistake.

To keep our discussion more interesting, please use examples that are not from our textbook.