While we dither on the planet, are we losing resources in space? Nick Bostrom has an article on astronomical waste, talking about the vast amounts of potentially useful energy that we're simply not using for anything:

As I write these words, suns are illuminating and heating empty rooms, unused energy is being flushed down black holes, and our great common endowment of negentropy is being irreversibly degraded into entropy on a cosmic scale. These are resources that an advanced civilization could have used to create value-structures, such as sentient beings living worthwhile lives.

The rate of this loss boggles the mind. One recent paper speculates, using loose theoretical considerations based on the rate of increase of entropy, that the loss of potential human lives in our own galactic supercluster is at least ~10⁴⁶ per century of delayed colonization.

On top of that, galaxies are slipping away from us because of the exponentially accelerating expansion of the universe (x axis in years since Big Bang, cosmic scale function arbitrarily set to 1 at the current day):

At the rate things are going, we seem to be losing slightly more than one galaxy a year. One entire galaxy, with its hundreds of billions of stars, is slipping away from us each year, never to be interacted with again. This is many solar systems a second; poof! Before you've even had time to grasp that concept, we've lost millions of times more resources than humanity has even used.

So it would seem that the answer to this desperate state of affairs is to rush thing: start expanding as soon as possible, greedily grab every hint of energy and negentropy before they vanish forever.

Not so fast! Nick Bostrom's point was not that we should rush things, but that we should be very very careful:

However, the lesson for utilitarians is not that we ought to maximize the pace of technological development, but rather that we ought to maximize its safety, i.e. the probability that colonization will eventually occur.