Put simply, dopamine neurons monitor dopamine, a chemical that accompanies good or pleasurable things — like, say, finding some rare loot in Diablo. Dopamine neurons subsequently try to predict when good things will happen in the future.
The site further notes that dopamine neurons “really go nuts when an unexpected, unpredicted gush of dopamine shows up, giving you an even bigger rush.” In other words, unexpectedly stumbling on that rare item brings even more pleasure and causes the brain to want to repeat the process. To put it even more simply, the site states that the reaction is similar to the one many people get when playing a slot machine. Winning is entirely random, but that doesn’t stop the brain from trying to figure out a pattern.” —The psychology of a gamer’s search for phat loot
Neiman Marcus actually was the first to sell gift cards, in 1994, but because the retailer didn’t quite understand their potential, the cards were kept out of sight and sold only as a novelty item. Blockbuster was the first to display them, starting in 1995, which was the true beginning of the gift card revolution.
Starbucks was the next major innovator, in 2001, with gift cards that worked more than once, so you’d have to keep going back.” —The Vile History of Gift Cards and How They Came to Destroy Christmas - Presents - Gizmodo