The main mistakes that traders make are:
1. Lack of knowledge: This is the most common reason that people dont have enough market knowledge and how to predict market.
2. Greed: Thats the human nature, in the greed to earn more we often lose many things.
3. Panic: People often cant control their emotions when they see their investments falling
It is true because trading is the very sensitive matter if you see then you will know that trading is full of profit but the mentioned mistakes some time will reduce your profit,. If you dont have knowledge about trading then increase your information first then go for trading, dont be rush to sell if you see the price increasing, wait for it to increase more and more, panic selling make the profit low so dont panic wait more and more so these will increase your profit and will cut your lose.