The main thing that's broken from the perspective of #3 is that it looks at a best-case scenario with no legal or political hurdles, and assuming the detailed c

The main thing that's broken from the perspective of #3 is that it looks at a best-case scenario with no legal or political hurdles, and assuming the detailed construction part will not present any surprises (and surprises that massively increase costs). But from that perspective conventional HSR is easy and cheap, too. You could sketch out a reasonable LA-SF HSR system with optimistic assumptions and put a $15 billion pricetag on it. It also has the benefit of being technically validated, and implemented in practice: Japan, France, and China have all built working systems for per-mile costs in that range or less. The California HSR issues have more to do with a mixture of politics and the U.S.'s "unique" regulatory setup, and it's not clear how hyperloop plans to sidestep those, even assuming the technology works exactly as envisioned. If Musk has some secret on how that's going to happen, I'd like to use it to just build conventional HSR! Put differently he seems to be offering a technical solution to a problem that didn't have a technical bottleneck, and it's not even clear the technical solution works.