The big thing is to get people off world, learn and innovate to make it easier. Ultimately you want at least one backup plan for the human race so if we all die

The big thing is to get people off world, learn and innovate to make it easier. Ultimately you want at least one backup plan for the human race so if we all die due to who knows what (giant asteroid, gamma ray burst, yellow stone going off, etc) the human race can live on. Musk has been interviewed before saying he wants at least one large group of people acting as a backup. It would be a shame if we stayed on Earth hoping to get the technology to make a place 100% hospital before leaving; who knows how long that would take and how much innovation we'd lose out on for not being bold.