To my knowledge, there was never a time where a mining gear took 20 months to ROI unless you plan on making it so by paying a fortune for a terrible mining gear at the worst time one can buy.
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If mining becomes completely unprofitable for mining farms, all mining profits will move to home miners, things might be a lot more profitable than they are now, but certainly not as much as they sell now, which might also make production cost more expensive,thus makes the numbers above way off.
Well, that's my point, remember we're talking about a scenario with no price increase and halving drop.
If home mining will be profitable with no (bulk equipment buys, preferential electricity rates, more efficient gear) I highly doubt you will ROI under 12 months. If you start making a profit without those advantages in six months you can surely bet industrial-scale mining won't be going down which...would keep home mining at bay...never-ending circle.
Second, what is home mining?
I stopped mining when the gear hit new levels of "efficiency" because of the noise and power, right now I could still probably run 3-4 s9 in my home but probably I would look every time at the breaker when both my electric oven and dishwasher are running during summertime along with the air conditioner as our circuits here won't be able to handle more than 7.5 kw.
Now I could use my parent's farm for mining as just one cereal grinder there is 30kw and is not used permanently but...
Would then I will still be a "home" miner?
And more important, those who buy these miners, as many as they would be, they would have to buy only a few 1,2 max 4 of those,?
Because the moment you buy 20
home miners... it makes no sense why you wouldn't buy 4 big ones that are 5 times more powerful, right?
This is the problem with targeting the so-called home miners, it's a very tight niche.
Hobby mining, that's something else, and this is why I would love a cheap silent miner that anyone could run just to support the network and that wouldn't make you raise an eyebrow when the bill comes. But that's wishful thinking and I know it.
Well from bitmain's viewpoint isn't it easier
Pump the price of LTC to 150-250 dollars
Then build L9 7nm or 5nm LTC miners.
At 200$ the daily reward for LTC mining is 1.4 mil.
With no price rise and drop in reward bitcoin would still generate around 7 mils a day.
After the BCH pumping loses probably they've stopped with the stupid plans...I hope....