Korach. R' Yerucham Levovitz, based on the mishnah in avos that korach was a machlokes shelo l'shem shamayim, says, that Korach was perfectly good in his actual deed, but only he had the wrong intent. In what way do we find that this was different from the claim of  'lamah nigara' when the jews werent happy about their loss of  opportunity for the korban pesach?

We learn the halacha of Ma'alin bakodesh V'LO MORIDIN from the story of korach. From the pans that the k'tores was offered in by Korach's group. If the halacha states that we must go up in kedusha, why does it have to state that we may not go down?
A similar question is dicussed regarding the din of zochin l'adam shelo b'fanav, v'ein chavin.... why is the ein chavin needed? the answer given is that even if there is an overwhelming z'chus to be done on behalf of another, so that the condition of zachin exists, however if ther is ALSO a chav involved the z'chus cannot be done.

similarly, by Korach we find that besides for his desire to rise in kedusha - ma'alin bakodesh, however he also was very clear to include "lama tisnasu" - the bringing down of another. when the ma'alin also incorporates the moridin of others it is a clear sign that the wrong approach to aliyah is being used.

we should all strive for greatness without any detriment and downfall of others, then perhaps we will all be elevated to kulam kedoshim with the right approach and intent.