A simple explanation of the economics would be great! Along the same lines as what @neoxian was getting asked - "where the money comes from." Whenever I talk about Steem I too get asked that all the time.
My explanation of Steemit usually goes:
"It's Reddit, but where upvotes actually pay. You can make money and invest in the platform, or simply cash out and pay bills. It is funded essentially through the traders of Steem along with institutional investors signing up to be apart of a new form of next-gen user reviews and content."
But I know this isn't 100% accurate and I feel like a better more succinct explanation is out there.