From my experience, here are 4 reasons I discovered:
1/ Lack of Discipline— a) Not sticking to one strategy, b) not respecting your trading rules, c) not sticking to your plan.
2/ Lack of knowledge—Inadequate understanding of the market, trading strategy, financial instruments, and fundamentals can lead to poor decision-making.
3/ Not having a mechanical trading system—This leads to emotional trading. Decisions driven by emotions like fear and greed rather than rational analysis result in significant losses.
4/ Overtrading—Taking many trades will affect your decision-making ability and lead to poor decisions.
If there are other reasons why traders lose money, share them with me.
There's a lot of reason but i think the number one reason is the emotion, if traders cant control the emotion the greed will follow and if the greed follow it will affect the decision that we make and it will end up losing, this is normal we can all experience this kind of trouble that is why traders that has so many experience mostly earn than the new trader because they can already control thier emotion above the market condition.