The Modern Curse of Overoptimization

I know a guy who used to make his living as an eBay reseller. That is, he’d find something on eBay that he thought was underpriced so long as the auction didn’t go above X dollars, buy it, then resell it for more than he paid for it Classic imports-exports, really, a digital junk shop. Eventually he got to the point where, with some items, he didn’t ever have physical possession of them; he had figured out a way to get them directly from whoever he bought an item from to the person he had sold the item to, while still collecting his bit of arbitrage along the way. This buying and selling of items on eBay, looking for deals, was sufficient to be his full-time job and pay for a mortgage. But the last time I saw him, a few years ago, he had gotten an ordinary office job. He told me that it had become too difficult to find value; potential sellers and buyers alike had access to too many tools that could reveal the “real” price of an item, and there was little delta to eke out. He’s not alone. If you