For example, let us suppose that you are stuck on a spaceship that has enough food and water to last one person 3 days in space. Let us also assume that your trip will also take you three days. In this case, you would want to make sure that you conserve your water and food. However, what if you are making a similar trip, but in this ship you have enough food to supply 100 people for a year. Now, the fact that you do only have a limited amount of supplies, enough to last you 100 years, does that mean that you need to be worried about conserving your supplies during your 3 day trip? Not really.
Now, the question is, what ship are we on? Are we on a ship that only has enough resources that we need to make sure that we conserve, or do we have enough so that we don't really have to worry about it. I think there is significant evidence that we live on the ship with an abundant supply of resources, and we really don't need to worry about conserving our resources. To me, these people talking about our need to conserve our natural resources are like people telling the individual with 100 years worth of supplies on a 3 day trip that he needs to make sure that he conserves his supplies, because he only has a limited supply.