When people are renting and don't own their own home, the incentive to actually improve the property isn't there, so an extra expensive space heater that can be moved to the next place has more value than improved insulation.

> you can probably heat the house the same with less energy

No, a 1000 watt heater is just as efficient as a 1000 watt computer in heating.

That's true but a 1000W heat pump can get you 3000W of heating. I.e. if you use a given amount of energy to transfer heat from the outside, you effectively get more than 100% (most heat pumps are at 300% efficiency).

You confusion is a failure to understand what heat pumps are doing.

An electric heater uses 1000W of electricity to increase the energy in an air volume directly.

Heat pumps use 1000W of electricity to transfer energy from one area to another.

In the former case, the energy in the warmed air is entirely from the supply of electricity.

In the latter case, the energy in the warmed air comes from the intake air and the electricity is only used to move that energy around.

So absolutely a heat pump using 1000W of electricity can move 3000W of thermal energy from the hot side to the cold side.

This, by the way, is why you're absolutely right that efficiency is variable, as it depends on the energy gradient between intake and output.

>Efficiency can't be higher then 100%, if it could be then you've got a perpetual motion device or in other words, you're creating new energy that didn't exist in the universe before - breaking physics.

Only in a closed system, heat pumps are not a closed system, they take advantage of ambient heat in the environment which brings efficiency above unity if measured as power input vs heat output.

It is called appearant efficiency and it can be and usually are greater than 1.

But yearly deprecation cost of a 1000 W heater is significantly lower than that of 1000 W computer equipment usable for bitcoin mining.