> If you are able to pull off that kind of hashrate, you might as well just be a good player at that point, as you would be making $50,000 every 10 minutes at current prices.
You’re missing my point. If there is a pile of unused unprofitable hardware (because energy efficiency is too low given the mining rewards), then you can’t use it to make an honest profit. That means that it has very little value to honest miners and might be sold for a non-crazy amount of money. A dishonest buyer could use it to mount a 50% attack for a few million dollars of electricity, but I bet a dishonest miner planning such a thing could arrange to benefit in an amount far exceeding a few million dollars.
(I bet that the actual major cost would be the connections involved in acquiring the power, not the power itself. But there are many, many GW of working-but-idle non-base-load power plants in the world. You can’t buy their power at rates that make honest mining profitable, but short-term dishonest mining may be an entirely different story.)
Some people may attach considerable value to the destruction of bitcoin if nothing else.
But you missed the fact that the difficulty is increasing at a rate that makes old un-efficent hardware mostly useless, even in big numbers.
Even ignoring the power required, you'd need 67+ MILLION AntMiner S3s, and those still are just barely profitable if you are able to get power for $0.03 per KWh, and are still sold for over $100 a piece.
I'd be willing to wager that even if you were able to buy every single S3 that exists you wouldn't even be close.
So... what happens if the price of Bitcoin stabilizes and then drops enough such that even the most recent generation of miners are no longer profitable if all of them are running?
In that case Bitcoin might be caught in a "big freeze". Bitcoin takes about 2000 blocks to adjust difficulty, so if it becomes worthless overnight, the amount of hash power could drop enough that no new blocks will ever be found, and without any new blocks the difficulty will never adjust.
So one player would need to buy the vast majority of all miners, and even then they would only be capable of doing a double spend attack on a dead blockchain.
You’re missing my point. If there is a pile of unused unprofitable hardware (because energy efficiency is too low given the mining rewards), then you can’t use it to make an honest profit. That means that it has very little value to honest miners and might be sold for a non-crazy amount of money. A dishonest buyer could use it to mount a 50% attack for a few million dollars of electricity, but I bet a dishonest miner planning such a thing could arrange to benefit in an amount far exceeding a few million dollars.
(I bet that the actual major cost would be the connections involved in acquiring the power, not the power itself. But there are many, many GW of working-but-idle non-base-load power plants in the world. You can’t buy their power at rates that make honest mining profitable, but short-term dishonest mining may be an entirely different story.)
Some people may attach considerable value to the destruction of bitcoin if nothing else.