I don't think we're alone. But I do think we're kind of trapped in our Solar System along with everybody else. Interstellar travel is so outrageously expensive that by the time you have the technology to do it you necessarily have the technology that makes it unnecessary.
An interstellar journey means you need a ship that can survive indefinitely in deep space, where you don't get free energy from solar panels or have easy access to comets to mine for materials. An in-system habitat has to be a solved problem before you can even consider building one. But at that point you have effectively unlimited living space, energy, and materials so why bother?
Even if your sun is turning into a red giant you can move your habitats to the optimal distance to sustain life. It's really hard to imagine a time when Humans have used up the entire mass of the other planets in the solar system and need to look outward for resources. You could build an almost unimaginable number of O'Neill cylinders using only the mass of Jupiter.
An interstellar journey means you need a ship that can survive indefinitely in deep space, where you don't get free energy from solar panels or have easy access to comets to mine for materials. An in-system habitat has to be a solved problem before you can even consider building one. But at that point you have effectively unlimited living space, energy, and materials so why bother?
Even if your sun is turning into a red giant you can move your habitats to the optimal distance to sustain life. It's really hard to imagine a time when Humans have used up the entire mass of the other planets in the solar system and need to look outward for resources. You could build an almost unimaginable number of O'Neill cylinders using only the mass of Jupiter.