Oh, I've got to admit, I'm a huge advocate of space development- in no small part because a single decent sized metallic asteroid could fuel the Earth's demand for metal for several years, obviating the need for destructive and toxic mining of the Earth's crust. Other reasons as well.
But yeah, we need to seriously learn to manage our waste and our resource overconsumption on this planet as well.
If we sensibly look after what we have already we won't need other planets. No problem with space travel - I saw the first moon landing! JV
For me it's more a combination of risk mitigation (not keeping our eggs all in one basket) and a need to explore.
Very sensible. Stick to it!