Proof Technology has been Lost: the Pyramids of Egypt

I am quite interested in evidence of advanced technology having existed prior to being lost. I note evidence is unequivocal of this having happened, and the Pyramids are good examples.

If you have interest in the history and development of technology, this is a good source, as these machining operations aren't possible to us today, and obviously were at some unknown point in the past.

Clearly, Egyptology and archaeology are claiming impossible events as factual and proved, such as that the Pyramids were made with hammerstones and copper chisels. Many speculate that there is a psyop involved, however, I note that successful publication results in larger grants, and suspect that mechanism alone is potentially causative of much disinformation. This does not exclude psyops or political motivation from being involved. It just does not require such to motivate idiots and liars from claiming false explanations are factual. People provably lying does not exclude stupid people from making false statements. Both, sadly and demonstrably, exist concurrently.

I was struck by the claim that these holes taper. Tapered holes are not the result of using a hollow tube as a bit, as the sides of the hole, as well as the core, will interfere with the bit.

There is no obvious mechanism that is able to drill a tapered cylinder. Even a bit that was shaped as a thin wire that circled the core would necessarily result in interference with the core and sides. Nothing that remained straight could produce such a taper. Even if you angle such a bit slightly to create a taper, the curve of the profile would interfere with the bit.

I'm baffled. Any ideas on how such a tapered cylinder could be produced?