This is a stub of an argument that I don't necessarily agree with, but that I think deserves to be thought about and analysed more.
Why would we expand into the solar system? What's the actual point - what would we get out there?
I'll argue here that there may not be good economic reasons to go to space; therefore space colonisation would be driven by non-economic reasons, which suggests a different pattern of expansion.
The revenues of space
How could we make money in space? The obvious answer is mining. Asteroids and planets are full of resources, carbon, iron, gold, rare earths, and so on; the value of these resources, at current prices, is staggering.
But note "at current prices". Obviously, if we brought down a few trillions of tons of copper, the price of that metal might suffer a slight dip.
So what's the economic value of current mining? Well, mining represented of world GDP in 2016; but roughly of this is coal, which is mainly used for energy (we'll get to that later). This is a small fraction of the current economy, and one that is in decline (over the century span, if not the decade span).
The attraction of space mining is that we have access to immense resources; but what we need is access to resources at a cheap marginal cost. If space mining doesn't offer that, then we just won't use it, just as there are ways of getting resources on Earth (eg some forms of recycling, distilling resources from the sea, very deep mining) that we are just not using because they're currently too expensive.
Or, put another way, if you're thirsty, the glass of water a metre away is of more interest than the vast reservoir just over the mountain range.
Other revenue generators
There are other things we can do in space. Some scientific experiments require micro-gravity; we can harvest energy via solar panels in space; new manufacturing methods may be usable in zero-G.
But these things can be done in near-Earth orbit, on some nearby space station, or on the moon if we really need some gravity or some mining. Deeper space seems to have little economic advantage. Is it any easier to design AI in space versus doing it on Earth?
The incidental economics of a colony
It's possible to do some agriculture is space; solar energy collection can be done almost anywhere; water is a useful resource for a colony, and, of course, once you have a colony anyway, shipping resources back might be relatively cheap.
But these are all things that make a space colony "not quite as expensive". They are not reasons to have a space colony in the first place. In no sane world would it be cheaper to do agriculture in deeper space and ship that to Earth, as opposed to doing that on Earth or in near-Earth orbit - the technologies that allow the first also help the others.
Why we would go to space
This doesn't mean that we won't go to space. We might go there for exploration; for military reasons; for tourism; for prestige; for escape. And once there are space colonies, they may become self-sustaining, and have trade with Earth. But resource economics is not why we'll go there in the first place.
And a military/exploration/tourism/prestige/escape expansion into the solar system will look very different from an economics driven one, and would be far less predictable.