I don't understand why people complain about the ROI even at low power rates.

At $0.02 per KW, you are profiting on average $320.00 per month for each S7 (more if you rent out or use good pools and have good luck). Yes difficulty is going up, but even then, mine for 6 months, sell after than for at least 1/2 your cost and you've made a good Profit.
Difficulty will not be jumping up at a constant 10% which people seem to be panicking about. That's just absurd. If anything it will average out a few % per month over a year.

You've still made a bunch of money for absolutely no work, other than sit on your butt..
:Shrug: