Sounds like you weren't putting consistant numbers into the calculator, or the calculator itself was broken or incomplete.
Might also be that you're looking at $ income not BTC income, that WOULD have varied a lot more as BTC price moved around.
no i was looking at the btc value, all the time, as i've wrote there in btc too, the profit remained for a very long time around 0.01 then there was a higher peak around 0.011-0.012 and now the little decline to 0.0097
Its because difficulty was pretty stable during this year, right now its going to go way up because of the next batch/ASIC manufacturer war which just started. Its winter so its a great time to start deploying a lot of miners. Pretty sure all the companies were just waiting for it.
So expect S5 profitability for now to drop and everything should stabilize after the miners catch up with the next gen of hardware.
i can understand this, but this will only lead to a new long way where the profitability will remain again constant for a long time but not with the s5 this time, but with the s7
nothing will really change, the diff does matter, i'm not saying the opposite, my point is that it is overestimated by a long shot
what it matter the most is your electricity cost and the iniital investment
Then indeed, it's the cutoff point for people based on their electricity cost. For most Americans, S5 are going to get bumped off and they will all need to seek more efficient hardware.
Difficulty will always adjust based on overall power cost/overall hardware efficiency. Which means people everywhere in the world that mine with a small margin will probably always be on the losing end.
In essence, anyone that's mining at electricity significantly costlier than the global average will probably always see difficulty as their biggest enemy, while people that pay less than the average know that it'll always balance out for them so they can run the same hardware for probably a gen longer.
Like S5 will totally survive for me during the S7 phase, since S1 is still just barely profitable to me at the moment.