There's nothing we can do to "fix" the risk of an unknown/unidentified space object hitting Earth at high speed and ending human civilization other than establishing self sufficient human cities on other objects.
But, more importantly, it is a misconception to think that the people GOING to Mars will have their lives improved. Life on Mars will take a very long time to become as good as life on Earth. But the tech developed to make living on Mars possible will help people on Earth.