TIME gets at the psychology…
I’ve found that sale-obsessed shoppers ultimately spend more money than non-sale shoppers. Consumers fixated on deals and discounts often purchase things that aren’t truly satisfying—and because they aren’t satisfied, they continue to shop. Additionally, the rush these consumers get from snagging what seems to be a bargain (85% Off!) has an addictive quality.
The story’s key points: we fear missing out on a good sale, and assume quality and value based on retail price. This lets stores emphasize “savings,” even though you’re only really saving money if you would’ve bought the item at full price anyway. Often, the purchases are impulsive. Shopping can also be a competitive sport especially when demand is low, and waiting and watching for sales is time consuming.