The True Collectors will notice the decline of the value of their product and begin to become nervous. The True Collectors are life-long collectors. They feel icky if they can't find a product to collect. However, don't worry, True Collectors, a new collectible will come along and divert your attention. Many True Collectors will never sell the items that they have collected, but they will not buy any more new items if they perceive that the items that they already have are losing value.
True Collectors are REAL collectors.
Real collectors are not bound to any one item nor do they have any real loyalty to any one item. The True Collector could talk obsessively about a particular item for months and months and then seemingly forget the item exists. The True Collector won't consider that they took a loss on the item. They will selectively remember the highest value that the item obtained, and then the True Collector will smile and move on. When the True Collector leaves the market, the new product begins to overflow on the shelves of the now irritated retailer.