Most of it is just a lengthy belaboring of the obvious - we didn't evolve on Mars or in space, so it'll be difficult and dangerous to go there.
There appears to be a well-hidden point, however. If we're trying to get away from the beasts that are destroying our habitat, the ones killing off native life, the ones spewing pollution, the ones who invented nuclear weapons that might kill us all, the ones who slaughter humans by the millions over petty arguments, etc... Well, we are those beasts. We can't get away from ourselves by taking ourselves to another planet.
It's possible that an asteroid might take us out, but that's unlikely enough that it wasn't even worth mentioning in the article. More likely that we are the greatest threat to our survival, and "Wherever we go, we'll take ourselves with us."
I read the closing paragraphs. The take away I got was instead of trying to colonize Mars, let's use the same brain power and resources to fix our problems here on Earth.
Yeah. It's kind of unfortunate that some people still think that by simply focussing all resources on one problem you can solve that problem. Has that ever been the case? Or even possible?
Either way, we do things off Earth for the same reasons we do things out of our towns and countries. It has been working out pretty well for us so far.
