The BBC has an interesting article [bbc.com] on short-term thinking in humans, and attempts by various people to get society to think long-term instead.
People tend to value rewards received in the future less than they value the rewards received now --- in the sense of "I'd rather have a hamburger today than 10 hamburgers three weeks from now". Coupled with improved technology, this has lead us to the 24-hour news-cycle life that society is in now: we are inundated with "breaking news items" that use up our stamina and we never take the time to think long-term. In practice, this means we tend to use up resources without making provisions for kids, grandkids, or descendants 1000 years into the future. We use various rationalizations of this behavior (when confronted with the accusation), but careful analysis shows that we are mostly wrong (as long as we value individual future humans as much as individual humans alive today).
While it's a fairly long read, I think it's worth the time: some ideas that I've heard before are placed in a wider context, and there are several references that I, at least, wasn't aware of.