Final answer:
The phenomenon where someone gives a positive review to an expensive but low-quality purchase to justify their decision is known as post-purchase rationalization or buyer's Stockholm syndrome, also related to the concept of a 'lemon.'
Step-by-step explanation:
What you're describing is known as the post-purchase rationalization or the buyer's Stockholm syndrome. This is a cognitive bias wherein someone who has purchased an expensive product that turns out to be of low quality may give it positive reviews or refuse to acknowledge its faults. This behavior can be a way for the buyer to justify their purchase decision and avoid feeling like they have made a mistake. This psychological phenomenon is often linked with the concept of a 'lemon,' a term economists use to describe a product that turns out to have low quality after purchase. Moreover, the effect can be exacerbated when sellers have more accurate information about the product than buyers, leading to a market of lemons where buyers are wary of purchasing because they expect low quality.
Advertisers can also manipulate this bias through the bandwagon fallacy, making it seem like 'everyone' is buying a product and thus it must be good. This, combined with the common misconception that a higher price indicates better quality, can lead to incorrect assumptions about a product's worth and quality.