I think the issue with the irrationality is that it isn't random. If some people made a mistake 20% of the time, completely randomly, when deciding between two products, it doesn't matter too much, and the dollars flow to the person who trembles less. However, humans can be exploited to make more mistakes. Gambling companies are a clear example, but I think run-of-the-mill advertising optimizes to be exploitative more than informative as well. Thus, all the dollars get sucked in by people who are actively anti-social, instead of those that offer a better product or make fewer mistakes.