You are (or should be) responsible for your actions. We grew up listening to it and this concept is present in discussions about determinism and free will. If there is no free will, how can be there an individual responsibility?
Free will is the possibility of having the power to make a free choice. It has been discussed by science and religion and is still controversial. The deterministic thinking says that all events are caused in a necessary and sufficient way for previous events, that is, a person is deprived of freedom to decide and influence the phenomena that him/her takes part. In the other hand, libertarianism supports the view that people have free will and are the agent's actions that always produce the event. The latter concept is most commonly used in economics.
At the end of the day, we know that we are responsible for our actions. And these actions would not have been committed without free will. It was our decision. It is common today to assign the responsibility of things to others ... Outsourcing guilt corrupts you and prevents you from going futher, in life and in the market. We blame the government, a friend, the neighbor, the hole in the street, politicians and many other concrete and abstract beings, but we forget that the decision was made by ourselves. This is very hard to accept, that is way we have this tendency to outsource the guilt and responsibility. When you take your part in the error, you open the door for a new journey of knowledge to be started, once you can identify what are the most relevant factors about the error, and which are the secondary factors of error (here we can allocate the third party responsability), and try our best to prevent or avoid a repetition of this harmful action.
How being a trader help you with that?
You, as a trader, will go wrong. You will make mistakes. And also will blame the market, the big sharks, the speech of a president of the Central Bank or the "current economic environment". But it will be hard to look at yourself and remember that it was you who pushed the button. No one forced you to it. We have a natural difficulty in accepting our mistakes, and denial is a strong step in this process. Those who are released faster from the denial phase accelerate the acceptance stage that cause natural evolution as a trader and as an individual.