The idea of "ignorance" here is a type of slippery slope I would argue. Offhand it would seem that many (all?) profits made in open exchanges proceed from som

The idea of "ignorance" here is a type of slippery slope I would argue. Offhand it would seem that many (all?) profits made in open exchanges proceed from some knowledge advantage on the part of one party—or at least originate from a calculated risk taken in light of some knowledge. As a 'user story'; "I work in the field of <something>-ics, and suspect that <some products|raw materials> in <some industry> will be much <more|less> available in the coming years, so I'm going to go <long|short> on related stocks." I don't think many would say I'm obliged to inform the selling parties of my reasoning in some interest of fairness. (I'm not including the edge case of insider trading, but run of the mill, hard-earned expertise.) And at a more mundane level of analysis, c'mon—who doesn't know to at least do some web (text & image) searching before selling off something interesting (complex, artistic, hand-crafted, etc.) that you know very little about?