Re: Well, he might have a point, but...
"If the end result of terraforming and colonising Mars is just more of humanity cold, starving and despised, or at war, just under a different sky then it's all been for nothing."
That's true, but that actually has very little to do with Mars. You're basically saying that people still can't act nice to each other and think further than their next lunch, and that's a bigger problem than space exploration.
I agree wholeheartedly, but fixing THAT problem is the job of politicians and philosophers, not scientists. Dropping it at the feet of the people who just want to figure out how to go to Mars is both unfair and unlikely to result in good solutions.