[mvhvv]

One thing I think is missed from these kinds of back of the napkin calculations is all the bizarre thermodynamic side-effects you'd encounter if you were somehow able to drill an actual hole through the core without it collapsing. I imagine the convection currents would be extreme.

Not to mention how the pressure in the centre of the earth is extreme because of the weight of the rock itself. When you have a hypothetical uncollapsible hole, you're explicitly removing the vast majority of that pressure. I'd be curious to know how those actual values work out for a "giant chimney" model though.