While we're here: How do real-world incentive structures interact with the EMH?

In the same way that "No one was ever fired for buying IBM", is it true that "No one was ever fired for selling when everyone else was"? And would that mean someone without these external social incentives will have an edge on the market? For example, what about a rule like "put money into an index fund whenever the market went down for X consecutive days and everyone is sufficiently gloomy"?