content: I don't think Musk would be saying this if he had any real doubt. The reason is that in space terms 2025 is a whole heck of a lot closer than it might seem. Optimal trajectory for a Mars launch only happens once every ~2 years. That only gives us 3 launch windows (2018, 2020, 2022) before the launch that's going to be carrying people. They'll obviously want to do extensive testing of things like habitation and food production on Mars before sending people over there. And presumably they will be using some sort of automated technology to setup a habitation prior to launch. In other words to hit this deadline we're going to start seeing major Mars based tests from SpaceX as quickly as 2 years from now. And they'll likely begin developing the planet in preparation for humans in 2020 at the latest as if something doesn't work as expected you'd like to be able to rerun or modify it in 2022. That's an incredibly tight timeline so for him to still be sticking to 2025 is very telling of their behind the scenes progress.