Mars can't be inhabited by people. Why does the United States still say that it immigrates to Mars?

There is nothing absolute in the world. Mars is not suitable for human habitation, but don't you know the human ability? It is still possible to build an area suitable for human habitation, just like the space station. Who can say for sure what will happen in the future, and there may be factors that human beings have not discovered. In short, the future is full of all possibilities, but I just don't know if our generation can catch up!