I went deep into the Yud lore once. A single fluke SAT score served as the basis for Yud's belief in his own world-changing importance. In middle school, he took an SAT with a score of 670 verbal and 740 math (maximum 800 each) and the Midwest Talent Search contacted him to tell him that his scores were very high for a middle schooler. Despite his great pains to talk about how he tried to be humble about it, he also says that he was in the "99.9998th percentile" and "not only bright but waayy out of the ordinary."
I was in the math contest scene. I have good friends who did well on AP Calculus in middle school, and were skilled enough at contests that they would have easily gotten an 800 on the math SAT if they took it. Even so, there were middle schoolers who were far more skilled than them, and I have seen other people who were far less "talented" in middle school rise to great heights later in life. As it turns out, skills can be developed through practice.
Yud's performance would not even be considered impressive in the math contest community, let alone justify calling him one of the most important people in the world. Perhaps at the time, he didn't know better. But he decided to make this a core part of his self-identity. His life quickly spiraled out of control, starting with him refusing to attend high school.
Do I need to comment on this one?