Why is it so difficult to make money in trading?

Some people will say that I don’t have the brains, and some people will say that my skills are not in place. These are not the real reasons. The real reason is that you cannot achieve unity of knowledge and action, and cannot enforce orders. People who have been in real trading for a few years and have lost a lot, are very clear about which methods are not good, such as not setting stop losses, adding positions when losing, heavy positions, resisting orders, frequent operations, running away when making a little profit, and holding on to losses. Many people die from these old habits, but the fucking thing is that even if you know you can’t change it, you will jump into it again and again even though you know it is a pit.