I don't know enough about the science to have a strong opinion, but I've heard a lot of people who have been critical of hyper loop, a very expensive tunnel fil

I don't know enough about the science to have a strong opinion, but I've heard a lot of people who have been critical of hyper loop, a very expensive tunnel filled with Tesla cars in Vegas that has much less efficiency than a subway from 50+ years ago, and saying that full self driving would be easy and finished years ago (he's since said full self driving is actually much more difficult than he initially thought). Maybe no visionary is going to get everything right. But there do seem to be some pretty major areas that have received critical feedback from people who seem to understand those domains.