Is It Possible To Sell Something At Twice the Market Price?

There was someone I used to interact with on Facebook a lot who was constantly harping on human irrationality. I remember him presenting me with the example of someone taking advantage of a hungry person’s moment of weakness by charging that person twice the market price for a sandwich. I remember thinking this was a silly scenario and needing to know how exactly the seller managed to get such a high price.

Is it a sandwich shop selling similar sandwiches to its competitors at double the price? If so, it’s hard to imagine they stay in business long. And besides, the buyer, weakened by hunger or not, can simply anticipate the higher price and shop elsewhere. Or does the owner charging normal sandwich prices, but spotting hungry customers and jacking up the price at the register? I find it implausible that this strategy will work long, unless there is a monopoly on sandwich-production.

Is it a chance encounter? Am I returning to the office, sandwich in hand, and a hungry, desperate coworker who doesn’t have time to walk a couple blocks flashes me a cool $15? In this case, it’s not clear that the buyer is overpaying. In this market of “desperate chance encounters”, perhaps the price of a sandwich really is $15.

Is someone closely monitoring signs of hunger in its potential buyers, preparing to rush-deliver them a sandwich? Perhaps they have an app, or even malware, installed on your phone monitoring your stomach for gurgling noises. Or maybe there’s a less creepy/illegal version of “predicting when someone is going to be hungry and delivering them a sandwich.” In a case like this (again, under a non-creepy version of "predicting the demands of hungry customers"), the seller is providing a service that other sellers aren’t. A hungry customer might be happy to pay for the added convenience. It’s possible they have higher operating costs to cover, justifying the higher price. Again, the "market price" might be twice as high in this particular market for perfectly legitimate reasons. 

I love hypotheticals. But taking them seriously requires thinking about how likely they are to actually happen. Learning from them requires considering how the answer changes when crucial details are changed. There might be ways to profit consistently and repeatedly from someone's irrationality. Overall, though, the "humans are irrational so markets don't work" line of reasoning misses the mark. It's vastly overplayed.