I wonder if we're making too many assumptions about how civilizations would live and spread. I've always wondered why our species puts so much focus on planeta

I wonder if we're making too many assumptions about how civilizations would live and spread. I've always wondered why our species puts so much focus on planetary colonization instead of building smaller habitats. We seem to assume we'll terraform Mars, maybe build habitats on some of the Jovian moons, then jump to the next star. It seems more logical to me to take the ISS and iterate on it, building larger habitats and learning how to live in them. There could be trillions of habitats out there and we'd never know it. From small low-orbit stations orbiting home planets to larger complexes orbiting their stars instead up to generation ships moving to the next star to mine for more resources or to build more ships due to population limits being hit. Once you've perfected the building of habitats that are large enough and are tailored to your species specific needs, why mess around with planets that can kill you in so many different ways? Maybe the reason we don't see anyone is because we can't resolve even very large habitats at light-year distances and the reason we don't run into them is because we don't have anything they can't get somewhere that isn't already inhabited. Perhaps they avoid inhabited systems because of the dangers involved.