Korach and Shabtsai Tzvi

 The commentary of the Netziv regarding the rebellion of Korach makes a nimber of assertions.

1) This was a revolt of gedolim against Moshe and ultimatey against G-d!

2) The motivation of the rebels was different. Korah wanted power. Dosan wanted to cause trouble and was utilized by Korach to recruit the 250 gediolim who were not only judges in Moshe's beis din but were known fot their piety and they sinned for the sake of getting closer to G-d

3) He notes that Nazir is described as were the 250 as sinning against their souls. He says the commonality is that the Nazir afflicts himself to develop ruach hakodesh. Something he is not deserving of by his spiritual level. They felt that only by doing the avoda of Cohanim could they get closer to G-d and they were willing to sin and die to accomplish that. That is why they were not swallowed up as their fellow rebels but were were burned by holy fire as were Aron's sons, He notes that the message of Tzitzis is that spiritual greatness can only be achieved correctly through mitzvos and conforming with    G-d's plan and not through sin. 

Bottom line the Netziv here explains as he did with the meraglim that gedolim also have a yetzer harah to sin even for the sake of Heaven as well as for baser reasons such as power or jealousy.