"Demand destruction" doesn't literally mean all demand is destroyed; it refers to the demand curve you reference. But as a sibling commenter notes, real business is rarely as clean as an econ textbook. In the real world, a supplier can contract to supply more units than they can actually produce. Their customers rely on the representation to make other related deals. And of course, the supplier can book the contracted revenue, causing investors to rely on the forward sales. They can't raise the price at that point, it's fixed in the contract. So if it turns out they physically can't deliver when the time comes, some number of the deals have to be blown up, causing related deals to blow up, etc., etc. That is the risk I was referring to.