I have absolutely zero knowledge which would qualify me to talk about this topic. But based on what I know about our world and its ecosystems, I just can't imagine that drilling holes into earth and extracting it's heat can be a good idea when done in large scales.

I could imagine that this seems reasonably safe right now, only for us to find out that it's actually a horrible thing to do. As has happened lots of times before. This is just a gut feeling and I'm not anti or whatever, it just feels...weird to me.

No idea what the bad effects could be. Loss of internal heat, destabilization, sinkholes, loss of pressure, volcano eruptions back-firing through these holes. Admittedly, these examples sound like apocalypse movie scenarios. Which just validates my initial statement about me actually not knowing very much.