He's relying on generating fuel on Mars, which considering that we've barely scraped the Martian surface with robots is highly speculative. Mars travel is still beyond business planning and into the realm of futures studies. I love SpaceX, but they haven't yet demonstrated they can reliably deliver payloads to Earth orbit on a regular basis. They're a long, long way from Mars.
I've heard some experts in the field say that the hardest parts about space travel are the launching and the landing. The middle parts, like the long boring flight and keeping the crew alive and not crazy, are massively easier and less risky in comparison, engineering-wise. They've shown they can put something into orbit. Landing on Mars with humans will be tricky, but the technology seems to exist to allow it, and that general kind of thing has been done before. Parachutes and thrusters, etc.
I don't doubt that SpaceX can get to Mars eventually, maybe even within 10 years. I really hope they do, I'm rooting for them. But I seriously doubt they will be ferrying space tourists out there for $500K apiece in any timeframe that would fit in a business plan, even a very long-term one. We're decades away from that kind of capability.
