Well first you aren't making money out of thin air.  You can think of mining new coins as "buying them" using your hardware & electricity.  Currently you are buying them at a continual loss.  The second thing is the network has a concept called "difficulty" which adjusts.  More hashing power = higher difficulty = harder to solve a block.  You won't break even in a week because even if you bought one you would be at the end of the line.  Long before you received your unit difficulty likely would be 10x to 20x higher than it is now.  Redo your calculations with difficulty being 20x higher and use some realistic electrical costs.