There are presumably lots of people and we’re stuck in a light cone with finite mass and energy that needs to be enough for everyone. You can spread out to reach more stuff but there’s a big empty gap after you run out of solar system and need to jump to the next star and a much bigger, emptier gap when you run out of galaxy and need to jump into the next one. And you can think up weird things like accelerating a solar system you’re in to 0.999x the speed of light to do relativistic sightseeing that you probably aren’t ever going to accomplish even with future supertech.
There are presumably lots of people and we’re stuck in a light cone with finite mass and energy that needs to be enough for everyone. You can spread out to reach more stuff but there’s a big empty gap after you run out of solar system and need to jump to the next star and a much bigger, emptier gap when you run out of galaxy and need to jump into the next one. And you can think up weird things like accelerating a solar system you’re in to 0.999x the speed of light to do relativistic sightseeing that you probably aren’t ever going to accomplish even with future supertech.