Korach תרל”ו 2

וְעַל פִּי פִּשּׁוּטוֹ יֵשׁ לִלְמֹד דֶּרֶךְ אִישׁ הַיָּשָׁר בַּעֲבוֹדַת הַבּוֹרֵא כָּל שֶׁעוֹלֶה מִדְּרִיגָה יוֹתֵר. יוֹדֵעַ חֲשִׁיבוּת כָּל דָּבָר קָטָן.
Simply we can explain that it comes to teach us, that the correct service of HaShem is that the more one becomes great, the more one appreciates something small.
שֶׁהֲרֵי מרע”ה שהי’ כַּמָּה מַדְרִיגוֹת לְמַעְלָה מֵהֶם הֵבִין חֲבִיבוֹת בחי’ הַלְוִי’ שֶׁנִּתַּן לָהֶם מהשי”ת.
For Moshe who was many levels greater than them (Korach and his band), understood the preciousness of being a part of the tribe of Levi, that was given to them from HaShem.
וְהֵם הִתְנַשְּׂאוּ. והי’ זֶה לְהַרְאוֹת לָהֶם עַל אֲשֶׁר אָמְרוּ וּמַדּוּעַ תִּתְנַשְּׂאוּ כו’ הֶרְאָה לָהֶם כִּי אעפ”י שֶׁזָּכָה לְכָל אֵלֶּה הַמַּדְרִיגוֹת חָבִיב בְּעֵינָיו כָּל דָּבָר קָטָן וְגָדוֹל בַּעֲבוֹדַת הַבּוֹרֵא וְלָכֵן זָכָה לְכָל זֶה.
yet they (were actually the ones that) raised themselves above the rest of Bnei Yisrael.
Moshe was responding to their accusation of Moshe and Aharon, where Korach claimed “why are you Moshe and Aharon elevating yourselves”. Moshe was showing them that even though he had attained such a high level, nevertheless every level big or small, in service of HaShem, was precious to him, and therefore he attained such a high level!
לְאַפּוֹקֵי הֵם שֶׁמִּיָּד זִלְזְלוּ בַּשֵּׁרוּת שֶׁלָּהֶם וּבִקְּשׁוּ יוֹתֵר:
As opposed to them, who immediately disregarded their service they had been given and deanded more.