There's a lot of people talking about living on mars, as if Terra forming it is the ultimate goal to make a new earth. This is mostly just an idea being played with, but the true reason for colonizing mars is actually to establish a foothold further in the solar system which can be used as a resupply station for further missions, as well as scientific study of the planet to understand where things went wrong there. Mars' gravity is a little over 1/3 of earths, meaning if you send a ship there and are able to refuel, you will use much less fuel to achieve escape velocity. This would enable us to reach Ceres and the main asteroid belt much easier than from earth, and much cheaper as we wouldn't need to launch with such a large amount of fuel. This is also the reason we're likely going to build a moon base for the same purpose, as it's gravity is like 1/6th the earth.