Who decides who dies? Who does the killing? What if you or your family members are chosen for death? Who sets up the new, minutely populated utopia? Who runs it? What rules are there?

It's not a simple solution, and it certainly isn't humane. Those people have lives, they have desires and friends and family just like you. They are not anymore "useless" than you or I or anyone else.

The people you are talking about are peasants. The majority of the population. They make possible everything in our life. Fresh fruit during winter, cars, computers, our homes... You would have them killed because you don't think they are useful? Ever heard the term megalomaniac?

...The real problem we have is anger, greed, arrogance, ignorance... not people. People are the most dynamic intelligent beings on this planet, we have the most potential of any creature. Our potential is vast and has produced many good things over the years. But, with the light there's the dark. If you want a solution to humanity's problems then start with yourself, your own mind. That's the basis for all of our contrivances.