"Why do you elevate yourselves over Hashem's congregation?" [Korach 16:3]
Such is the nature of a dispute that is not for the sake of Heaven, noted R' Simchah Bunim of P'shischa. It blinds the eyes and closes the hearts of the quarrelers, so that they lose their common sense.
For the Torah testifies about Moshe Rabbeinu: "Now the man Moshe was exceedingly humble, more than any person on the face of the earth." How could anyone possibly accuse him of possessing the contemptible trait of arrogance? Yet this is exactly what Korach and his assembly did, as the verse states: "Why do you exalt yourselves over the congregation of Hashem?"
Rather, this is the way of strife, the power of impurity that accompanies it totally corrupts an individual's intellect.
Source: Rabbi Yisrael Bronstein