Passion For Power
The Midrash brings two reasons for the punishment of Nadav and Avihu. The first was that they lost their lives because they refused to get married.
The second reason was because of their desire to take over for Moshe and Aharon. They asked, “When will these two old guys die so that we can lead the generation?”
The Gaon Maharam from Vilna, pointed out that the two reasons are really intertwined. If they didn’t want to marry because their “souls desired Torah,” as was the case with Ben Azzai, then they should not have desired positions of leadership.
It is obvious that when one needed to carry the burdens of the community, it would take away from their Torah study time. This proved that their decision not to marry was not based on their passion for Torah. It appeared that their passion for power was greater. Therefore, both reasons were connected. They were worthy of punishment for both reasons, which were really the same reason.
It should be clear that Hashem knows man’s true intentions. People might try to fool themselves, but they cannot fool G-d.