Quote from: dinotom on January 12, 2018, 06:16:41 PM

Given the average rate over the past month or so, we are going to be approaching a difficulty number with a 5 handle, from its current 2 handle.

This will absolutely crush even the Antminer S9 profitability unless bitcoin doubles or more from here.
This is the single biggest issue I see in mining now.

When I first decided to buy the Antminer S9 in late November, I noted that slushpool had about 48,000 workers (Early Dec.), I will be getting my miners shortly, but now slushpool has almost 74,000 workers and in the next two months that's probably going much higher. And I'm sure its the same at every pool, including Kano which I'm likely to be joining. But I can't see how these miners stay profitable past July-Aug at current rate of increase of mining machines and difficulty.

What are you long term miner's thoughts on this subject?

I suppose we all have our spreadsheets to look at the profitability of mining. Unfortunately there is a lot of guess work of BTC price, miners cost, difficulty/network hash rate. My spreadsheet show that one should be careful when buying more miners -

If I start mining tomorrow I should have paid max. $200/Th (all in) else loose money and is better off buying BTC with the money(including power cost) . This is based on-
- Bitcoin price double in the next 12 months from $14600 => average 2.5% growth per 2016 blocks (anyones guess)
- Network difficulty increase 11% per 2016 blocks (possibly low)
   Historic compound growth over periods(2016 blocks) back from 13 Jan 2018
   5.1156%   Growth over 52 periods
   6.6199%   Growth over 25 periods
   7.4302%   Growth over 20 periods
   7.8076%   Growth over 15 periods
   9.0211%   Growth over 10 periods
   9.9122%   Growth over 5 periods
- Block reward per block 15 BTC (after pool fees)
- Electrical cost $0.14/kWh (no growth)

Buying a S9 miner at $4000 => ~$295/Th is out of the question for me. Even at electrical cost $0.07/kWh; $265/Th is break-even. I can afford $200/Th => S9 landing cost of $2700 mining from tomorrow.

Things to consider
- Im not sure if the manufacturers can keep pushing out hashing power at 11% every fortnight. If we sit at BTC say ~16Eh/s then to increase at 11% every 14 days => S9s per period (~130 000 ; ~145 000; ~161 000.... ). BCH also need miners. Maybe someone has better insights here.
- Seeing for public we pay in BCH at Bitmain, mining(when more profitable than BTC) or buying BCH when price is low drive down $/Th

No use keeping eyes closed and just buying miners when its cheaper to buy BTC.

When all is said and done - Mine on!