Because Korah was proud and trust himself too much, he went against Jehovah arrangement (Nu 16:​1-3; w11-E 9/15 27 ¶12)

Korah was having plenty good-good work to do and people use to respect him (Nu 16:​8-10; w11-E 9/15 27 ¶11)

That bad way of thinking put him in serious trouble (Nu 16:​32, 35)

We must not allow what we able to do in Jehovah service to make us to be proud and trust ourself too much. If we na stay long in the truth and get plenty responsibility in the congregation, that the more time we must be humble.