After watching Superman II, I realized an interesting dilemma inherent in many supervillain schemes. In Superman II, General Zod and his Kryptonian two cohorts arrive on Earth with the aim of conquering the planet. And within a period of a few days, Zod and company bitch-slap the military and humble the President on National Television. Superman is elsewhere mining the depths of his heart to discover the meaning of true love which, as we all know, is fairly time consuming. But for Zod it was mission accomplished. Not like George Bush in Iraq, because Zod's mission was actually accomplished. Zod ruled the world. And then he got bored. Really bored. A particularly amusing scene shows the Zod and company sitting in a shattered Oval Office zoning out.
Which brings me to the dilemma mentioned earlier. If a supervillain's goal is to rule the world, will the prize be more interesting, or will the effort? Once Zod ruled the world, he was bored because there was nothing else to do. Until Lex Luthor walked in, informing him that the Son of Jor-El was living on Earth and waiting for a beat down. But prior to that, Zod believed he had truly conquered the world and everything in it. That means that he owns everything and all of Earth's assets are within reach.
But do any of Earth's resources have any value when you already have everything? The traditional means of economic valuation (like supply and demand) completely break down when one individual has complete control of supply and therefore has no demand. And supervillain rule is unique in this respect because a supervillain has direct control even beyond what a leader would have in a monarchy. Literally, everything belongs to the villain. And if you disagree with the supervillain, they will incinerate you. That's a pretty definitive way to establish ownership.
I believe Mark Waid's series "Empire" was exactly about this sort of thing. What does a supervillain do once he has control of the world? Unfortunately I didn't read that series, so any insights contained therein are not available for me to use.