In a supermarket, at the potato chips aisle, I find myself caught in a dilemma Suppose I love potato chips and consume about 10g of chips a day, should I buy a 50 g packet for €2 or a 100g packet for €3?
Well, if I were an entirely rational person, I would naturally buy the 100g packet. It is a better deal, and is likely to last for 10 days. However, in real life, there is a side effect – my rate of consumption of potato chips is proportional to the quantity of chips at my disposal. The moment I have a large packet of chips on my kitchen counter, my consumption goes from 10g a day to 30g a day, until that packet is nearly empty. In the bargain, I have consumed more and spent more.
Marketers are aware of this tendency. This is why they offer us bulk discounts and try to increase the batch-size of whatever we buy.
In a world plagued with consumerism, buying exactly what we need – nothing more – can appear costly at first. But this added cost is an investment to guard against our own irrational tendencies.