I gather you've been (are still?) a miner, so your opinion has weight for me.
Please help me understand.
The cheap (subsidized) electricity argument... yeah, that is probably a show-stopper
However, wouldn't an assortment of algos make life harder to monopolists/producer firms by forcing some kind of specialization?
Besides, they might have GPU farms (I believe they do), but in that case they would still be competing with homespun rigs set up by people who fire their computers anyway, mining or no mining. At the moment, given the monopolist market, few independent actors have modern mining equipments able to compete. Do you think the number and power of "independent" GPU's is too small to be significant?
Yes, people use their computers anyway. However, running a GPU 24/7 at maximum capacity uses a lot more electricity than a computer sitting on idle for most of the day. An assortment of algos only makes it difficult/impossible to make ASICs, which are dedicated chips designed to only do one task very well. Since GPUS are more general purpose, it's only a matter of changing the software to mine a new algo. It is true that an independent miner can possibly find ways to minimize their electricity costs. They may live in an area where it is cheaper. The may also live in a cooler climate, so their coolings costs would go down. The real kicker though is a big guy will almost always be able to buy the equipment (the GPUs) for cheaper than the independent miner. It's the same reason why Wal-mart can get their goods for way cheaper than an independent grocery. I'm not an expert, but one factor is that the cost of shipping goods does not go up proportionately with the amount of goods transported. A bus may use more gas than a taxi, but it can carry up to 50+ passengers and doesn't use 10X the gas. Plus both the bus and the taxi each need only one employee to drive.