that's really true especially if you work as the most important trader and investor so you want to get rich quick and successful in your work. You have to be able to control your emotions and mentality because most people who fail are due to being unable to control eventually leading to wrong decisions.
most people when they make a profit, they will be in a hurry to double their profits, and eventually they suffer losses. we have to avoid such things, so emotional and mental control is very important.