There are many historical events in the world that have been changed by some insignificant little people. For example, the trigger for the outbreak of World War 1 was the assassination of Archduke Ferdinand and his wife by a small person, which triggered World War 1. From this we can see that a small person can change important history. If the little man hadn't assassinated the couple, I'm afraid there wouldn't have been World War 1. However, the disintegration of the Soviet Union was also the same, and it was also because of a small person that led to the disintegration of the Soviet Union.
First, a personal vendetta led to assassination
In 1933, there was a small man named Nikolaev, who was a propagandist at the St. Petersburg Institute of Party History. At that time, some party members had to work in the transport department, and as we all know, the transport department was very bitter and tired, so many party members were reluctant to go, so they planned to draw lots to decide, and as a result, Nikolayev was drawn. In the face of such a thing, Nikolaev can only say that his health is not good, he needs to be recuperated, and his wife and children cannot do without him for reasons not to go.
Because of his refusal, this person was directly expelled from the party and public office by the unit on the grounds of disobedience. But not long after, his party membership was restored and he received a notice to work at the factory. It's like being the equivalent of today's civil servants, suddenly becoming the lowest-level workforce. How could he possibly accept such a gap? So Nikolayev began to write letters to the leaders of the various organs, even to the Fuehrer.
In his letter, he wrote about the unfairness of the unit to himself, and after a period of time, no one paid any attention to him. Because he did not participate in the labor, he had no source of food and was able to rely on his wife alone to provide food. Then he gradually became degenerate and began his writing career, writing down his injustices and feelings in his diary. Because he didn't want to go to work, he had a lot of time to write at home.
After a long time writing letters without any results and no solution to the problem, this also made his mental thoughts more and more extreme. He even wrote in his diary that he wanted to create a shooting similar to that of Zhiryapov. Anyone who knows Russian history knows that Zhiryapov was a famous assassin in Russian history, and he assassinated Alexander II. From this we can see that he has targeted Kirov, the first head of St. Petersburg.
Second, assassination leads to disaster
After a period of time, he obtained a gun through proper means and had a license to hold it. On December 1, 1934, he assassinated Lokiev in the office building, and after the incident he did not choose to escape, and was arrested by the police who arrived. He was tried on the second day of arrest, and he also truthfully told the story of the crime. At this time, Lokiev's good friend Joseph directly began a historically disastrous movement on the grounds of Kirov's affair. Nikolayev was executed, and it didn't take long for Nikolayev's brother, her sister, and cousin to be held for trial.
Third, disasters trigger associations
After the execution of Nikolaev and his siblings, a large number of executions began, at this time of executions of people who were in a hostile relationship with Joseph. To put it bluntly, this is just a strategy for him to use the case to eliminate his opponents. Even in the absence of evidence, many competitors were quietly executed. The Russians believe that Nikolaev's actions are likely to have been planned by the Fuehrer, or that Joseph was planning to eliminate his opponents. The third possibility is that Khrushchev wanted to strike at his predecessor.
Summary: I have to say that there is no real answer to this matter until now. No one knows whether the young man had a murderous intention because of the transfer, or whether the young man was hired by Joseph. The diary may have been forged by someone else, or it may have been deliberately shown to people. The average person does not write a diary, he writes most of his plans in a diary, this is not a clear statement that he alone wants to take all the charges, it is likely that this person is just a victim.