Actually emotion can only make you lost the more important thing you better know is the news so you can sell it or buy it earlier when the news you heard might give high impact on the price. Emotion will only came if you make a late reaction even you already have idea about the given news and how these news will affect the market.
You are right, emotions will always make us to loose hopes in the market, even though people try to analyze the market situation, but sometime it will not help them to make a profit. Of course, sometimes the news from the company will not help us to reach our desired target and this will surely create panic for the trader.