Actually, losing is a part to every decision we make and nobody want to try this or nobody wants to lose money. And when it comes to investing, the fact that this is a possibility has unfortunately, turned a lot of people off and made them choose not to invest at all. I used to be like that, too. I was strong believer that when it comes to my hard-earned money, "its better to be safe than sorry."
Sometimes we need to take risks, as long as the risk is a calculated one then there is not need to avoid it, every time you drive you are in risk of crashing, but since you take the precautions necessary you reduce that risk at a minimum, the risk is still there but is now a lot more manageable.
No risk, no gains. Some people don't realize it, but even storing money in your savings account has a certain risk that people expose themselves to.
The main difference is the level of risk that people are willing to take, and what kind of returns are enough for you to be happy with.
Some people just want to save money where the generated interest will cover all sorts of tax expenses, and the other is looking for gains of +50% annually.
In the latter example you obviously need to understand and accept the risks as you depend on the markets everywhere in the world. Today's profits can turn into heavy losses the next day.