Earlier quoted context omitted.
The problem with this line of thinking is that it might be a little short-sighted. Since we are intelligent, we should be careful. With great powers come great responsibility. If someone doesn't like hurricanes, they can move where there is none. When Earth will be 99% inhabitable (because of air pollution, soil degradation, lack of water), is the solution just to say "oh well", let's go to Mars?
(I assume you meant un inhabitable) For the individual the answer is almost certainly yes. If we have the ability to survive elsewhere than earth and we have brought earth to the point that it is 99% uninhabitable then going someone else is probably the best choice. One could easily argue that our ability to consider our environment and make changes to our behavior accordingly is unnatural. Avoiding the above scenari…
That type of thinking will ruin the second planet just as much.