Because humen live there, and they can't live on Mars. Want a reason? First, humen need oxygen to live, and there is none in Mars. Second, we need water and water needs a water cycle or else it will run out. Mars doesn't have the appropiate cycle for the water cycle to work there. In the present, it is not posssible for humen to fix these problems. Or at least, the only possible solutions so far are only temporal. If all this is true, you can't dissagree with my answer.
Because of its ability to substance life
