1) You can think that there are hundreds of OTHER things worth pursuing, instead of spending time on a project that is very hard to complete, expensive, and benefits (initially) only a small fraction of the world's population. Myself, I'd rather improve public trasportation in both SF and LA, instead of focusing on the Hyperloop. But there are people willing to spend some time to tinker with the idea. Let them do it.
2) They might not be successful, but they are sparking a discussion on transportation, technology, and government. Having a discussion is healthy, and needed.
Good luck!