If you have the capability to bore a hole through the center of the earth, you would be so much more advanced than the current state of the art, that our puny earthling money wouldn't buy you anything you couldn't get in easier ways.
I was just wondering if hair thin, hollow, reflective tubes could be made cheap enough for oceanic data cables. It would obviously be more expensive than regular fiber.
And the advantage wouldn't be that big. Especially compared to co-locating.
You can't colocate at two stock exchanges at once, which is required to make use of the arbitrage opportunities the article talks about.