My question is why 
What is affecting the reality of bitoin mining and is not taken into account in the calculator I referenced?
What is affecting the reality of bitoin mining and is not taken into account in the calculator I referenced?
Try: http://btcinvest.net/de/bitcoin-mining-profit-calculator.php
You could easily get profit with minig if the difficulty doesn't increase. Bitcoinx.com does not have a option to make a monthly difficult grow. Your 3 months based on a difficult of 707,408,283.