Businesses that often price their product low (e.g. by advertising a "generous" discount) unwittingly attract a group of consumers known as "cherry pickers". Cherry pickers are customers who exclusively seek and buy these products and leave without buying anything else.
They are usually older people, over 55 years old, who have a lot of free time - sometimes retired or on a low income.
Having sufficient information (e.g., by thoroughly studying store brochures, TV commercials or offers posted online), they are willing to literally go the "extra mile", from store to store, in order to buy what is discounted or at a low price.
For example, many supermarkets sell 50% off ready-to-eat, private label packaged foods that expire soon. Therefore, many people go first thing in the morning and buy multiple packages in order to get a cheap meal.
These customers constitute a problem for these businesses because they do not buy other items at regular price while in the store. In short, the stores are actually losing money every time these shoppers shop. For this reason, many businesses have introduced upper limits on the quantity of sales items that can be purchased at the same time.