Yeah that was the first example I thought of too in terms of recent cautionary tales. I think there are some key differences though, namely that as a Life Science company, the scrutinity and examination of Theranos' tech is much much harder to prove with certainty. It's why drugs have to go through such extensive trials to be brought to market.
There's a certain amount of seeing is believing to Magic Leap. If I were to wear a Magic Leap headset and was able to play the game that they demo, I would sign on in a heartbeat. You can fake a demo, but you can't fake the game. And I'd imagine investors at this valuation/amount of money (which btw is 10x what Theranos raised total!) are definitely getting into the nuts and bolts, making sure that the tech isn't being faked.
I used to think along this line too. But examples like Theranos make me more skeptical