Difficulty won't rise exponentialy forever. In a year it can be at 300M, which will make AM still profitable (energy-wise).
Difficulty does not have to rise exponentially forever. It just has to rise 35% month-over-month, for merely 12 months, and the buyers will never make their money back: https://bitcointalksearch.org/topic/m.1889860
For the record, 35% per month for 12 months would bring the network to ~2000 Thash/s total, which half of it is already being built or planned by various entities (100TH-Mine, BFL, ASICMINER, OEM Avalon Chip Customers, etc).
As I suspected/predicted, difficulty continued to increase significantly. Those who bid 75 BTC for a 12.8 Gh/s blade in late April 2013 never made their BTC back. They spent 75 BTC to mine ~40 BTC so far. They will never mine more than ~45 BTC in the rest of the lifetime of their equipment. Holding BTC would have been smarter.
I guess these blades have at least sentimental value, being some of the first ASICs.
Yes oh great profit tell us what next. Blades were one of the most retraded ASICs ever.
Overpriced Yes,retarded NO !!!!!..........at least they didn't do the preorder crap..............................
I get dyslexic...........