I will illustrate the massive game-changer that the SpaceX BFR will be. I will show this by describing how we can have millions of people in space by the 2040s.

Gerard O'Neill visions from the 1970s failed to be realized because launch costs in the 1970s were 300 times too high. SpaceX BFR will cut costs 400 times lower than Saturn V.
 

Within a few years, space capabilities will transform.

How many people have ever been to space? .. about 540 over 60 years
How long have they stayed? Only about 15 days or less only a few handful have stayed over 200 days

How Many could we have in living in working in space by 2045? the population the USA had in 1776 at its founding .. 2.5 million people.