Sure, but I'm sure there were engineers at Theranos who thought their tech was going to be a game-changer as well. Being confident in a product doesn't mean the product is actually any good.
> Not delivering seems incredibly untenable.
I would happily place a bet they will never deliver, or if they do deliver it ends up being lackluster and nowhere near what they originally promised. They showed a demo video two years ago (that turned out to not actually be a demo), and haven't released anything since.
Technology does not stand still in that time: in 2015, the iPhone had a single rear and front-facing camera. Soon you'll be able to buy one with stereographic rear cameras and a dot-projection IR depth mapper on the front, with what is from all accounts an extremely good AR software framework.
Oculus, Apple, and Google aren't just twiddling their thumbs waiting for Magic Leap to release a product. They are actively putting money into R&D, and shipping iteratively. Apple's going to have real-world AR experience and feedback from iOS 11 and the iPhone X that Magic Leap won't have.
I'd love to be wrong - it'd be great to have another player in the space, and maybe their tech is awesome. But if you look at what everyone else is doing compared to what they've released...it doesn't look good.