The company use this to trigger people to buy the product at any price and immediately because they know that once the products are over, they do not have a chance to keep one for themselves.

psychology is the study of experiences that arise in humans, both the senses, mind, feeling and will. Most people may only focus on psychology that studies human personality. However, this human learning activity can actually be seen from various aspects, namely social, educational, criminal, organ function, medical, religious, industrial and many more. For those of you who are focused in the business world, "psychology also embraces the world of marketing."