There's also the question of how much of the electricity is paid for. E.g. how many miners are mining on "free" electricity at their parents house, or have access to rack space with "free" electricity (our racks at work come with a certain amount of power, for example; someone putting a Bitcoin mining rig in there would not increase our costs as long as the power doesn't exceed certain limits), or has a miner in a quiet corner at work or similar?

Or any number of other ways of getting free / outright stealing electricity.