awsome response by gavin:
I enjoyed listening to your remarks from the recent Cato's monetary conference.
It will be very interesting to see how mining plays out over the next couple of decades; I don't think we know whether it will turn out to be very centralized (like the web searching market, with Google dominant), or pretty decentralized (like the general purpose computing market, which used to be very centralized in the era of mainframe computers but is now radically decentralized with all of us carrying computers around in our pockets).
I tend to think that we'll end up somewhere in the middle, because while there are economies of scale, there are also diseconomies of scale. Waste heat is a huge problem (as the datacenter fire in Thailand that took out a big Bitcoin miner shows), so spreading that out among lots of people where a little excess heat isn't a problem is a benefit.
Cheap electricity is a centralizing force, but my guess is that as miners figure out ways to use excess heat that might start to become important (mine in places with cheap electricity AND where the excess heat can be put to good use).
Mining in a pool requires very little bandwidth (just 80 bytes every few seconds to get a new block header to work on), so there is no centralization advantage for having lots of small miners.
Transactions are generated all over the world, so there should be no latency advantage to being in any particular geographic location.
In any case, it seems to me that there are so many variables that go into being a profitable Bitcoin miner (cost of electricity, cost of capital, access to latest chip tech... plus who knows what else in the future, maybe private deals with merchants for priority handling of their transactions...) that there is unlikely to be just one global optimum for the profitability equation.
And if you're correct, and there are economies of scale that will cause mining centralization that will destroy Bitcoin... it seems to me big merchants and exchanges should realize that is happening. In which case they might decide to sacrifice some short-term profits to invest in mining themselves to ensure the continued success of the whole system.
miners are playing a rough game. the equilibrium between greed and centralisation seems crucial.