don't even have to go that far to get a temp for a house that reduces heating/cooling costs by a ton. You just need to get to where its a nice room temp. drilling tech has improved and im hoping we see much more of it akin to rooftop solar.

well, AFAIK drilling such a hole would be very costly, you need to take into account that a lot of layers are solid rock and drilling through, maybe hundreds of meters of rock at hundreds of meters deep could make the project so expensive that it doesn't justify the energy output we could get out of it,

Geologist here and it depends on a coupme of things, I can walk you through them quickly :)

It hugely deoends on the geothermal gradient. On average the earth hrats by 25-30° per kilometer, much less if you have old continental crust (Middle of America for example) and a bit more uf you are in a zone of active rifting (Taupo Volcanic Zone in NZ, Oberrheingraben in germany for example). For it to be economically good a spot is needed wjth a high gradient and than a very warm layer of rock, which you only truly know kncr you have drilled.

But drilling is extremely expensive, we are talking multiple hundreta of thousands of euros per 100m-200m, but this can also vary a lot based on the rocktype you find and if you wanna keep the core or not. Not to sa it is slow, a hole of 1km takes probably a year minimum I think, but I am not too sure on tat part.

Next is the question if you wanna do open or closed system. You proposed an open system which is reasonable but you would need to find a rock layer that is a) permeable or fractures enough that the water could actually flow, b) not interactive in any way with water, c) stable enough that no small particles would be broken off by the water and then transported and accidentially fill the gap, thus killing the system. Yes this has happend before, its very unlucky. Closed systems are doable, but give less energy.

Also during all of the drilling and during the test of an open system the stress field of the rocks can change and you could induce earthuakes, not huge ones but maybe enough to damage a fee houses in close vicinity, if they are not build to withstand those. This makes it hard to do in big cities.

So yeah combining all of this its just costly and risky and not a lot of companies or goverments are willing to take the risk. Now do not get me wrong, once you have set everything in place this is basicly unlimited free energy, its amazing and definetly a huge possibilty that I am very muvh a fan of. And as others have pointed out there are spots in the world where this js easily doable, look at iceland for example. But Iceland also sits on a fucking mantle plum and is basicly a volcano, like best conditions for this. I think they once even drilled into a magma chamber on accident and they were jot that far down :D

Very low likelihood the water would come back.

What they do is sink closed circuits of piping, then run water through them for heating, which is geothermal, not hydrothermal. But that's expensive and depends on the depth to hot crust. In a thin spot, it's easy! Iceland's electricity is very cheap due to this. But somewhere the crust is really thick, like the center of a tectonic plate, it's a long way down. And, with long pipes, there's more risk of them being damaged if there's any geologic activity.

Iceland has loads to make aluminium with.

It does work. It's common in Sweden for home heating and hot water. You could input a little more heat if boiling water to spin turbines is your thing.

dont you mean geothermal, i think you are confusing it with hydroelectricity. geothermal uses ground temperature. currently we dont have the tech to use that, its mostly fictionaly used in scifi shows along with fusion, antimatter but with advanced tech.