Perhaps why I have such an affection for the guy.

...and I'm down with that. But as an entrepreneur, the path to success is to go buy lunch for some of your pet scientists and engineers and say "hey guys, I'm filthy fucking rich and I feel like building a Mach 2 tunnel under Bakersfield. What do you think?"

This gives them an opportunity to say "Hey, Elon, you're dope and all and Teslas are some of the sexiest electric cars ever made, but there's a reason nobody rides around in bank tubes, despite their invention in 1836. Maybe we could, I dunno, cure cancer or start an Ekranoplan company or something instead. We're more likely to succeed and that way you don't look quite so much like a toenail collector."

I suspect this happened and he was annoyed that those with half a clue told him he had none, so he went around them and said

"I'm not going to invest in this (because my peeps told me it was a batshit insane idea) but somebody should (so that if it works I still get credit). It'd totally work, I ran the numbers (based on the fact that I have no expertise in this subject whatsoever). KTHXBYE."

By the way, if you had an idea for a "mach 2 tunnel under Bakersfield", I'd at least read it. You're a hell of a writer.

Robert Heinlein envisioned a world encircled by slidewalks. He was a hell of a writer, too, but that didn't lead to their adaptation outside of airports and subway terminals.