We're at the bottom of a deep gravity well. The vast majority of us are never getting out of the well - unless you're talking about after a population collapse.

We're at the bottom of a deep gravity well. The vast majority of us are never getting out of the well - unless you're talking about after a population collapse. Thankfully, we're based on replicators - we could colonize the galaxy by sending out only small numbers. But barring some very far-future tech, each fertile world is going to carry a large immobile population, and we're going to have to learn not to trash planets.