Imagine if we solved this problem and over the scope of 40 years the whole world just went geo and dumped Oil, Solar, Nuclear?
Someone posted a more informed comment on Hacker News about 2 months ago. The idea is that if you drill to 5 km deep, let's say, you find very hot rock. But once you extract the heat from that rock, new heat is very slow to come because rock is a good thermal insulator. So, you'd need to produce secondary holes. Lots of them. In the end the math just doesn't work out by orders of magnitude.
It just costs more than wind and solar. Same as nukes. Unlike nukes, geo was once competitive without heavy subsidy, in places.
If you plan to drill the holes yourself, you have a lot of work to do. Drilling is expensive, and a single hole will not get you a lot of heat after the initial honey moon period.
Geo costs more than renewables, but that was not at issue. It is anyway cheaper than nukes, in places where it is used.