When first presented with the idea of the Hyperloop (a train running in vaccuum in an underground tube), I was extremely skeptical it made any sense. Sure it might work (after all the London tube started out as a pneumatic system much like those that older ones of us remember sending receipts around department stores). But did it make any economic sense. Was it really likely that, if we can't afford rail lines above ground easily, we could afford to build thousands of miles of air-tight large-diameter tubes? Honestly, it looked to me like any other silly idea on the cover of Popular Mechanics, right next to the titanium zeppelin the size of Connecticut that would someday be doing construction work.
So enter Elon Musk, who is very passionate about the idea, claims to be convinced it will work, and appears to be putting some money behind it. With his support, the idea must immediately be treated as more credible, and it does indeed get a lot of press. But here is the problem for me with Musk: With him, the idea must also be treated as very probably another attempt by him to drain money out of the taxpayers' pockets into his. Because that is what he does in so many of his enterprises.