וַיִחַר לְמשֶה מְאֹד (16:15) Look how angry Moshe became at Korach! And look at all the biting criticism he gave. He tells Hashem: אַל תֵפֶן אֶל מִנְחָתָם “Don’t accept their Korbanos!” “Did I ever take anything from them?” “Why aren’t you satisfied?” “Isn’t your elevated Levi status enough for you?” Look at the stark contrast between his strong reaction to Korach, and his zero reaction to: וַתְדַבֵר מִרְיָם וְאַהֲרֹן בְמשֶה (12:1) Miriam’s conversation with Ahron about Moshe when he was totally quiet & the Torah says: וְהָאִ יש משֶה עָנָו מְאֹד (12:3) Moshe was exceptionally humble.
In truth, a person who isn’t Sameach B'chelko deserves a severe tongue lashing. R' Shlomo Freifeld Zatzal once told me that he deserves a good whipping. Moshe’s severe anger and criticism is a Siman of how serious is not being a Sameach B'chelko. And he was dealing with the biggest giants in Klal Yisroel: אַנְשֵי שֵם (16:2) men of fame, etc. [and major Talmidei Chachomim]. Moshe’s message: It’s all worth nothing if you aren’t Sameach B'chelko.
And according to the Gr”a, the issue that caused Churban Bayis Sheni was because there was no Bitachon, meaning no Sameach B'chelko. Last week, the Torah dealt with the Meraglim who didn’t have Bitachon to overcome difficulties. This week, it’s the basic Sameach B'chelko aspect of Bitachon.