Rashi explains that these two reshaim, miscreants, who acted as Moshe Rabbeinu’s nemeses, going back to Egypt, were here again to do what they were good at: harassing and undermining our nation’s leader. When Moshe came by, they remained firm and resolute in their commitment to degrade and humiliate Moshe in every way. One wonders how these individuals survived so long. Eighty percent of the Jewish People who were in Egypt died during the three days of the plague of darkness. Dasan and Aviram did not. They continued their subversive activities at every juncture of Klal Yisrael’s journey. Yet, they were still here to join Korach, fueling his dispute. What merit allowed them to leave Egypt with the twenty percent who were worthy of the geulah, redemption?
There were a number of reasons to keep Dasan and Aviram on the scene, despite the many challenges they created as a result of their wicked nature. The Melitzer Rebbe, Shlita, explains that, at times, Hashem maintains the wicked person, so that others will derive a lesson from his bad example. Dasan and Aviram taught us the evil consequences of slander, when they slandered Moshe after he killed the Egyptian man that was harassing them.When they searched on Shabbos for the manna which Moshe had warned would not descend, they demonstrated the extent to which one who lacks faith in Hashem and whose desire for wealth is overwhelming, can descend.
Second, the positive actions of the righteous have greater radiance when compared to the negative actions of the wicked. Moshe and Aharon’s humility and quest for harmony among men becomes much more luminous when compared with the arrogance and controversy prone nature of Dasan and Aviram. Light is much brighter when held up against a dark background.
Next, if there would be no reshaim, wicked people, one’s bechirah chafshis, free will, would become stunted. Everyone is availed the opportunity to gravitate towards the tzaddik, righteous person, instead of the rashsa or vice versa. No one is compelled to do so.
Last, the Kedushas Levi writes that Hashem allows reshaim to exist, so that they can serve as the vehicle for glorifying His Name in the world. When we think about it, had there not been an evil Pharaoh, there most likely would not have been ten plagues, which brought about an unprecedented Kiddush Shem Shomayim, sanctification of Hashem’s Name. We can thank Dasan and Aviram for the earth opening its “mouth” and swallowing up these miscreants. Every person during his lifetime has the opportunity to become the vehicle for sanctifying Hashem’s Name. It is his decision, however, whether he wants to do this as a rasha or as a tzaddik. It is his own choice.