I did some looking around. Looks like I was a factor of 10 off. As in- not 1% but 0.1% and that could be sustained for millions of years

Other estimates suggest that harnessing just 0.1% of the Earth’s heat could supply the world’s total energy needs for two million years>

https://www.contrary.com/foundations-and-frontiers/geothermal

https://www.energy.gov/eere/geothermal/geothermal-faqs#:~:text=4.5%20billion%20years.-,This%20heat%20is%20continually%20replenished%20by%20the%20decay%20of%20naturally,essentially%20inexhaustible%20supply%20of%20energy.

There is also a great pdf over at www.worldenergy.org under their geothermal - world energy council that is a little old but still points out the math on just how immense the energy output of earth is. We could each run our own small AI data center on geothermal power and the earth would still have extra. And we are only talking about tapping into the very top of the crust.