The goal of investing is to sell something at a price that's higher than what the investor paid to buy it. The problem investors face is determining when prices are low enough to indicate a buy and high enough to decide that selling is the best choice.
Exactly. Also, when you are investing, you shouldn't mix your emotions with it. You should be mentally prepared. The moment you decided to trade, you should've prepared yourself for the worse. That there is always a chance that you could lose all your money. Investing is a gamble. A gamble in which you can earn a lot of profit given you know the right strategies and knowledge.
I am strongly disagree with that statement that buy high and sell low because if you can buy at a high price and then sale at a low price then you will always face a loss and you will unable to keep your trading through this strategy. You need to buy low and sale high and through this strategy you can make more profit.