Psychology can never be mastered, but to make the situation even more drastic is the fact that most people have not even completed the basics.
Psychology is difficult to master, it is not a one time thing where a trader can claim that they have mastered their psychology completely, but a continuous process of trying to attain and maintain that balance after it has been achieved. This is one of the major lessons that the recent dip in the value of cryptocurrency taught me. Many of the traders who took their lives are not new traders from what I observed, many already have experience in the market and have been trading for a long time even to the extent that people were able to entrust some money into their hands to trade with, to these persons they must have reasoned that they have mastered their psychology and nothing could affect them anymore, until the event of that day that led to many of them ending their lives.
What must be understood here that having time in an market does not make you an expert. This is a common confusion. Sure spending time in something does technically give you experience but not all experience is equal. What mostly happens is that time spent in the market when combined with some lucky successes deludes people into thinking that they are experts. Someone who has valuable experience and expertise would never over leverage themselves and especially not using someone else's money. That shows a high degree of psychological immaturity and trading amateurism.