You have to consider the total cost of ownership. The exercise goes like this. What is the total traveling population per year that would get from point A to point B that would ride planes if not for hyperloop (assuming it becomes reality). That gives you the number of planes that would be used per year. Need to consider per year, because a lot of traveling is seasonal. Then what is the cost to maintain those planes, operating costs like fuel and pilots, insurance costs for damages and risks, etc, etc.

I have no idea how the total cost of ownership would compare. But I wouldn't write off hyperloop just because it would be expensive. It may be possible to make it work. Given how much plane tickets cost, I can easily imagine people paying more money for something that's seemingly more convenient and safe than planes.

edit: The man figured out how to turn launching rockets into a profitable business. The man thinks it's possible to build a nation-wide charging station network that can charge all the cars his company builds for free. With this type of thinking, I think he takes cost feasibility seriously, so I'm curious what he has up his sleeve.

edit2: Maybe what I wrote above maybe sounds too much like hero worship. I'm not saying he has everything figured out. I'm just saying I'd be very on the fence and would not bet for him or against him, but most definitely not against him.