you don't understand why a builder with 10% of the hash loses money by expanding to 15% of the hash you think he makes more money if he does that.
the problem is 4-6 guys all have 10 to 15% of the hash each. they all can build bp and then the other 4-6 guys match them.
So what hey have been doing is swapping gear with out really expand hash by a ton.
they have s-3's at .75watts they have s-5s at .50watts now they have s-7s at .25watts
so they ⅓ their power so many think they will 3x their hash . if the top 6 builders all do this they all gain nothing and they spent money to make the gear.
so they try to ⅓ their power and 1.5x or 1.2x their hash.
if the top 6 builders do this. they keep the same share of the network and they spend less on power.
This is what has stopped the crazy growth the last year.
unless your gear is god like say .01 watts a gh and really cheap to build expansion of hash matching your efficiency gain is a loser economically.
so s-5 at .5 and s-7 at .25 for example does not pay to 2x the hash power
if the other builders can match you. but if antminer ½ the power and 1.25x the hash and are matched by the other builders antminer makes more money.
this is very simple math.
I believe there are several errors in your analysis. You have assumed everyone pays a similar amount for their miners, has similar costs and does not try to drive others out of business.
1) Not all miners pay the same for their miners. The mining hardware with the highest efficiency is not likely to be sold to the public. It is more economic for the manufacturer to keep it to themselves and mine themselves. This is what KNC and Bitfury do. They manufacture their own cheap hardware and do not sell to to the public. It is in their interest to increase their hash rate as it increases their profits.
2) For similar reasons miners in areas with the cheapest electricity will try to maximize their hash rates. Anyone who pays more than about $0.05 per kWh is likely to be ultimately driven out of the mining business.
3) Finally you have assumed people would co-operate if they all had the same costs. But people are not always that rational in an unregulated market. See the Tragedy of the Commons. https://en.wikipedia.org/wiki/Tragedy_of_the_commons
The entire mining game is a zero sum game. There is only a fixed amount of money available from Bitcoin mining.
The best way to maximize your profits is to not share your competitive advantage and to keep your costs below your competitors. Ideally you would like most of your competitors to give up and leave the market.
So I expect the battle between the miners to continue and the hash rate to continue to increase for some time yet.