Ego

There is a complicating factor that makes the handling of investment mistakes more difficult. This is the ego in each of us. None of us likes to admit to himself that he has been wrong. If we have made a mistake in buying a stock but can sell the stock at a small profit, we have somehow lost any sense of having been foolish. On the other hand, if we sell at a small loss, we are quite unhappy about the whole matter. This reaction, while completely natural and normal, is probably one of the most dangerous in which we can indulge ourselves in the entire investment process.

- Philip Fisher