It can be, assuming you are in the right location in the world. The problem is cost efficiency: you are talking about tens of thousands of dollars for a system

It can be, assuming you are in the right location in the world. The problem is cost efficiency: you are talking about tens of thousands of dollars for a system that will only pay for itself in a decade (often times; in some situations this is the perfect answer). Geothermal is no silver bullet unfortunately. There is physical efficiency, and there is economic efficiency.