That's the thing about it — space settlement, at least in the Moon (Mars is somewhat harder, how much we don't know, because we have no human experience yet, & O'Neill colonies have startup problems), is a realistic prospect. It is something which is feasible now, & something which people do want (not everybody, but some people anyway). What remains is to stop waiting around, & work to make it happen.
The first flight took place in 1903 and man first walked on the moon in 1969 - just 66 years later. So there was a generation that witnessed this first flight and the commercial airline industry grow. I was 6 years old when man walked on the moon. I remember thinking " Great if the space industry grows as fast as the airline industry, I'll be able to vacation on the moon during my lifetime." One of my life's big disappointments. :frowning: I guess there is nothing exciting or commercially profitable up there. Just a big rock. Now if it were made of cheese...
Emphasis is mine, because that (not government) is what makes industries grow. Private corporations grew the airline industry because there was profit to be made in it. Shoot, America was 'discovered' in searching for a trade route to the far east (a profit-making venture).
If extraterrestrial colonization is to happen, it will be because the private sector sees money in it.
Actually, there are a lot of extremely good profit opportunities we know about, & could actually begin to implement, today. Satellite solar power & asteroid mining are two very obvious ones. The main problem is that capital requirements are high & the big payoffs are typically 20 years or more out — it's just impossible to get commercial money for that kind of time these days. The US rail system was built on hundred-year bonds, but that was under the gold standard. There are some very credible prospects in the range of three years & sooner, which piggy-back on the long-term ones, but they don't stand on their own. Hence my position that the initial impetus has to be supplied by another means. In the past people have assumed that government would furnish the jumpstart, but it doesn't appear likely. I think I have identified a viable alterntive approach, & if not that'll just be too bad.