People keep bring up movies and books, so... honestly curious - about what? A Minecraft movie makes about as much sense as a movie about Battleship, and we saw how well that did...
Minecraft on the other hand has a giant fan base that loves it and will buy anything related to it. Just look at all the merchandise that's started coming out over the last few years and now is everywhere. It's basically Angry Birds 2.0, just 10 times bigger, and Angry Birds it's still making tons of cash.
Minecraft is huge right now, there's a lot of money to be made by someone who knows how to properly milk it for all it's worth and has no problem with doing so.
Also, the movie could be about teens who play networked and develop relationships in-game and out of the game.
Minecraft: The Story of Mojang http://www.minecraftstoryofmojang.com/
It was funded through Kickstarter.