With Elon, it's easy to give examples, because he could brush his teeth and will claim it's going to revolutionize everything.
The hyperloop proposed 10 years ago was supposed to revolutionize transportation and get you between SF and LA in an hour. It's totally dead in the water now.
The hyperloop is odd actually. Musk didn't actually want to do it, he just tweeted out some random thing as a reaction to the price of California's high speed rail proposal, but at that point his fanbase was used to him just doing crazy things so they piled on him. That's why he set up that competition, to see if it was viable.
Source: his biography
Besides, that it doesn't matter if musk just claims something, anyone can claim something. Anything he's gotten behind has succeeded.
The top speed recorded is 288 mph and hasn't been beaten in 3 years. This isn't even faster than the fastest train at 374 mph which doesn't need vacuum tubes. Considering that hyperloop is just a fast train in a vacuum to make it go even faster, you'd expect it to at least beat trains after 10 years of work. So you tell me.
I think it's supposed to be more efficient, not just fast. I worked with a guy who helped design Maglev trains for China. With my limited knowledge, I'd think that a train floating above a track with no friction and being propelled by a magnetic wave has more potential that a train in a tube. I'm not familiar with the power and technology it takes to create that magnetic wave, but I still think it has more potential. I should have asked how the wave was created, but I was too amazed that the technology even existed.
Idk, I think any argument that hyperloop is more energy efficient goes out the window when you consider the energy costs of having to keep depressurized a 500 mile long tube.