General Discussion

Mars is too inhospitable for human settlement. Our current technology is vastly inadequate for the job, not just the transportation but the large-scale terraforming required.

And the reason for terraforming's necessity is the most difficult and practically insurmountable obstacle in the idea: Mars has almost no magnetosphere. The planet is bombarded by solar winds that strip it of the elements needed to sustain life. Plus, there are cosmic rays to deal with as well.

The problem is just too big and if we had the tech and power to solve it, then we could save Earth from anthropogenic climate change first. But we don't. The Mars colonization pipe dream is a ridiculous waste of resources under current circumstances.