How do you look around at the legacy of colonialism on earth and be like "yes more of that please?"

There's an incredible amount of scientific understanding to be achieved over the next few decades using unmanned probes in the solar system including mars. After that we'll see. We are barely capable of manned spaceflight at all, don't even have a proof of concept of a self-contained ecosystem that can be isolated for years at a time. We are simply not politically and scientifically sophisticated enough to attempt this on the scale of decades. Leave it for the future.