Trading is full of surprises but traders must learn to take these surprises as normally as they can. In trading you cannot predict the rise and fall of prices due to the economic and political changes of a country. So if you stay unaware of a sudden change, you can lose money and get the shock of your life. So don't be surprised.
You could pick the best stock in the world at a rock bottom price but if the economy tanks in the short term, or the president was to be impeached (), these could be catastrophic for the market in the short term. If markets fall significantly then very few shares would be able to avoid the blood bath.
For sure, trading is full of unpredictability. Actually, there is no any thing you can fully rely on except your own skills and knowledge. So, each trader has to deal with uncertainty associated with trading process. In this situation the best thing you can do is to find your own approach to managing risk instead of trying to guess the future events. Numerous market gurus announce their predictions, but in fact they all fail in predicting the price changes even in short term perspective. That is why professional traders prefer to react on the events and follow the trends instead of trying to predict it. It is well-known that "trend is your frend" - of course, counter-trend strategies could sometimes also be profitable, but the risk in such case would be substantially higher.