Not possible unless you ve got really, really cheap electricity.
Cause there s nothing to prevent people to buy 120000000 rigs by mid 2018 and bring you out of business. We ve seen this before, in 2013/2014, market gets saturated and everyone shut down their rigs. The ones who remain are people with 6 cents per kwh and lower.
not true you can do good with 20 cent now and more, in 2018 the profit will be much higher, so evne with more gpu there will be the same profit, while it's easy to double the gpu when they are few of them it's more difficult when you have millions already o the market