"I'm surrounded by idiots." If that doesn't sound like a moment in many people's lives, then I don't know what does.

It's the story of his intellect and supposed superiority over his brother, and later envy for Simba's role as Scar feels as though he deserves the role. He believes he is so much better than his brother and, subsequently, his nephew. He is entitled to the role due to his superior intellect. It is somewhat subtle in the movie when he states the apparent physical difference between him and his brother. There is a temptation of intellect there where Scar conflates his intellect with the abilities and strength of character that are required by leaders and kings.

A sense of pride that he knows best on how to be king, sounds like other mythological characters we've heard of. Loki anyone? Hades? etc. It seems to be an archetype of such. Even in more laidback shows like Phineas and Ferb, Doofenshmirtz is the villain, and is an intellect. Though Phineas and Ferb are also genius craftsmen in their own right, so this seems like a separate case, but one worth noting. Intellect does not equate to character, and in fact can lead to resentment, envy, and much more evil deeds. And the story of The Lion King is the show of this to its ultimate fate.

Also, as a side note, there is an interesting contrast between dying for something good and being an angel in the clouds Vs living long enough to really become a villain and well...burn in a hungry fire. Nice Heaven and Hell contrast there. Just to tie the end of their fates, as Character is Destiny, and Intellect is not a substitute for good moral deeds.