There is nowhere else for the heat to go.
Aren't you forgetting that the efficiency of a thermodynamic process is proportional the ratio of the differences in temperature and the ambient.
For someone who trumpets regularly about his superior intelligence and his breaking insights into fields from physics to economics, you sure get a lot of the basics wrong. If a mining device uses X joules of electrical energy to perform Y hashes, those X joules get converted into an equal amount of heat
. This is basic conservation of energy.
What you're confusing this with is the Carnot efficiency of a heat engine working between a hot and cold reservoir to perform useful
work. Interestingly, a heat engine run in reverse becomes a "heat pump" and can be used to convert work into a
greater amount of heat at the hot reservoir side; it's actually possible to get 2, 3 or more Joules of heat output for every Joule of mechanical or electrical energy put into the heat pump (because this extra heat gets "pumped" from the cold reservoir)!
1For the pedantic, minus a negligible amount lost as EM radiation, etc.