Colonizing on Mars and beyond??

We hear big time that we need to colonize Mars in the near future as there is potential destruction of earth and humans should be ready to deal with it. My question is

1. We have the earth where we all live and thrive. But we are destroying it, by various means and are not bothered to safe guard what we have. But we are so much into travelling to Mars or some other planet where you don't know whether humans or for that matter animals/plants can live and thrive on those? There are lots of variables, like the basic gases for life, water, gravity and myriad of others we take for granted as we are already adapted to live in this environment on Earth. Or this travelling to mars, mining the moon etc., basically some one trying to make a quick buck at the end of the day in the name of advancing science.

I am not against the development of science and technology, but looking from what and how things are going, it looks like its more of someone or a corporation trying to make money at the end of the day than science or safety to humans?

Why not focus more to safe guard the Earth we have?