That's the difference between builders and consumers. People who are mostly consumers have a realistic number where they could stop contributing to society. Smalltime builders can imagine a lot of wealth, but at a certain point don't want to get too big. Big Dreamers are only limited by what they can imagine and make happen, and only infinite capital, labor, and time could achieve their dreams. Once you surround yourself with people dreaming of humans as multiplanetary, earthly levels of labor and wealth are obviously not going to make it happen.