I didn't mention it in the post but the video points out some people going to Mars would decide to return back to Earth. After a cargo ship drops off supplies on Mars it has plenty of spare room to accommodate return passengers. They need food though so I imagine that would require buying a return ticket. Maybe they'll have insurance plans to cover the expense if someone elects to return back. It wouldn't be quite fair to require everyone to buy a round trip ticket if not everyone decides to go back. It would be more fair to require everyone to pay insurance to cover the ones who want to return. Even if someone stays the benefit is they paid to get rid of the grouchy complainers.