To be fair, he did do that for kilos to orbit via reusable rocket, so there was a moment when everyone went "hmm maybe there is a TBM equivalent of the Falcon 9".

But presumably it turned out that actually Herrenknecht and Hitachi aren't stupid, whereas, say, Boeing had been leaving opportunity for radical cost reduction on the table.

There existed a well known path for reducing costs to orbit, and the market was non-competitive and highly non-optimized for decades. One single company made a single experiment in that path, and it was somewhere on the middle between success and failure.

That's not the case for drilling. The Boring Company has no clear proposition about how they would reduce their costs.