If that is the case, our current launchers are, for all practical purposes, the smallest they can be to support 6 people permanently in orbit. Falcon 9 (13.2 metric tons), Antares (6.1 metric tons), Ariane 5 (16 metric tons), Soyuz (6.5 metric tons), and H-II (10.1 metric tons) are the launchers for cargo to ISS. This is our baseline. On average, our launchers are 10.4 metric tons to low earth orbit.
If the astronauts lived like we do on earth, by how much will our launchers grow? I calculate that our launchers would have to be 19 metric tons on average for 6 people with 6 launches per year. You can see how that number already dwarfs our current launchers.
Now what if we had more than one space station or one big one, in orbit and a total of 100 people living in space full time? If they live like astronauts do now, they would need 380 tons launched from the ground annually. They will need launchers of 1,040 metric tons to launch 6 times a year.
Now if those 100 people lived like we do on Earth, then they would need 620 metric tons in a year. The launchers would need to be 1,900 metric tons for 6 launches.
Can you imagine a 2000 metric ton rocket launcher? That's about 17 times the size of a Saturn V. That is huge.
You might say what if we increase the number of launches a year? Won't that decrease the size on the average launcher? Sure it will. Let's see.... I calculate that for 100 people that need 620 metric tons a year and 20 launches, they would need average launcher size of 510 metric tons. That's still about 4 times the size of a Saturn V. Now 20 launches a year is quite a hefty schedule. I suppose if they spread out the load over 4 companies and/or countries it's not so bad. Though a 510 metric ton rocket is quite large, I believe it is within the realm of possibility to accomplish.
You can see how the number expand with the increase of people.
This is only to LEO. What about the Moon and Mars? Well the numbers get exponentially larger. So the rockets get exponentially larger. The ones we have now are puny by comparison. That is why people have suggested learning to 'live off the land' and reduce the need for new cargo from Earth. Even in deep space living off of asteroids and comets will be necessary. It's just too much for us to lift that much stuff out of the Earth's gravity well. The other thing we can learn to do is recycle, and recycle everything. Air, water, waste (yes No 1 and No 2), soil, plant matter, and parts are things we need to learn to recycle if we are to live in space, or on the Moon, or on Mars. New technologies are bound to be needed to this end. Are we up for the challenge?