>Since his name will come up, let's clarify that Elon Musk did not invent the idea of a vactrain.

No, some victorian era crackpot kook invented it. 150 years ago, all of these gadget-bahns were invented by some top-hatted jackass. He took all of his profits, from sending children to die in the mills, and put it all on his vision for the future. Then all of those ideas failed spectacularly and were left in the dustbin to die, until now; when the marvelous Mr. Musk comes along and decides to rebrand them as the future. Novelty is a brain poison.