The Medrash Tanchuma asks a question regarding the motives of Korach. "Korach was a clever man; what did he see that brought him to such foolishness? The medrash answers "His eyes misled him, for he saw a great chain of descendants emerging from him: Shmuel Hanavi, who was as important as Moshe and Aharon, as it says in Tehillim (99:6) 'Moshe and Aharon were among His priests and Shmuel was among those who invoke His name.'" Korach saw from the fact that Shmuel is mentioned in the same sentence as Moshe and Aharon, that Shmuel is just as important as them.
Korach's line of reasoning is very difficult to understand. He feels that he is justified in replacing Moshe and Aharon as leader because he saw that one of his descendants will be a very important person. How does his offspring prove that he is fitting to be a leader? If Shmuel himself was leading this rebellion, then the argument would make sense: Shmuel is just as important as Moshe and Aharon, so perhaps he could be fitting to lead in their place. But what does Shmuel's greatness say about Korach's own worthiness?
Furthermore, this thought process only proves the very opposite of Korach's entire goal! Inherent in his line of reasoning is the assumption that Moshe and Aharon are men of spiritual greatness. Korach deduces that since Shmuel is just as important as them, Korach himself deserves to lead. But yet, he claims that Moshe and Aharon are unwitting to be leaders but that they are fabricating the will of HaShem! How can they be great enough to prove his own greatness, yet not great enough to be the rightful leaders?
How can Korach make such an illogical and foolish argument?