The world is very large and we have a detailed accounting of what, maybe a fraction of one percent of it? It would be FAR weirder if we stopped discovering new things in a mostly unexplored planet.
You are exaggerating. but there is definitely more to find. some of the largest mines are just like the first place they started digging without any modern exploration techniques. Mostly doesn't matter. humans will run out at some point of critical materials.
Deepest human-made hole is about 40,000 feet and the Earth's crust is about 160,000 feet. We've barely scratched the surface, literally.
Good luck getting deeper, temperatures rise, everything becomes much harder, thus costly. You can't do any serious extraction of solid minerals, only gasses and liquids (oil) are possible in certain situations
You could craft that same type of argument about literally thousands of technical challenges from 200 years ago that are now thoroughly solved. Is this one super extra special?
How do you intend to reach 100,000 feet, much less conduct large scale mining?
How did people 200 years ago expect to reach 40,000 feet? Have a little perspective.
We don't have 200 years to figure it out. I'm not the one that lacks perspective here. Hard problems also often take over 200 years to solve, we can't rely on the dogmatic belief that we will somehow figure it out.
A failure to plan is a plan to fail.
This is simply not true as materials don't disappear.