People especially newbie ignore this stuff. Their goal is to have huge profit so they often tend to risk a huge percentage of their portfolio. They don't think about any risk and just think of the outcome if the market favors their side. They will just realize their mistake when their portfolio is more than 50% down.

Learning those strategies requires strong discipline to control their emotion which is the most important for me to avoid huge loss in trading. Even experts sometimes forget their trading strategy because of greed.