Back? I thought it was a one way trip.
For some, I'm sure it will be.
Being away from the protections of Earth is not recommended for long periods, and even the shortest trip to Mars, its layover, and the return opportunity back to Earth exceeds three years or more.
The radiation penalty alone for this amount of time is pretty much a lifetime dose.
Musk speaks of our becoming a multiplanet species, but things will have to change before that can become a reality. Maybe just something as simple as heading for Venus instead of, (or as well as), Mars.