Well to each his own but I buy it. We humans as a crowd are amazingly destructive....easily much more so than any other creature on earth. And i know the world is huge, has been around long before us etc etc. I just think that we are completely capable of screwing up this planet and making in unlivable especially as the population grows and I think we impact the earth and atmosphere much more than some folks think. We do that by screwing up the balance of things. And I also think people as a rule tend to take on an "it can't happen to me" attitude that completely blinds them to doing things with some foresight, common sense or an eye towards prevention.
Seriously.....folks just can't be bothered.

These are my thoughts but I seriously wish I had Mark's passion (goddamn youth)