At some point it will be worth it to mine asteroids and bring the stuff back down to earth. I think that point will be when the scale of the mining is absolutely huge, and the infrastructure is amazing, and the price of the stuff we're mining (gold, platinum, etc) is substantially lower than what it is today.

It all comes down to whether you can get stuff from LEO to earth and earth to LEO really cheaply. If you can do that, then our economy will go grab this stuff and someone will make a lot of money doing it.

> space colonies will export intellectual property

Not for a long time though. Earth will have an advantage at making IP for a very long time. People will do research in nice places on earth rather than in cramped & dangerous conditions in space. The exception is microgravity research, but that's already a thing. Of course as the cost to LEO goes down we will do more of it. Eventually someone will commoditize it and you will be able to ship a container of a certain size with your low-gravity experiment to LEO for a fixed fee.

Space is only cramped to minimize surface area, if inflatable habitats or some other form of assembly was used, structures can and will be much larger.

Sending materials to Earth will cost as much as sending them into space, as the materials must land safely and be recovered as efficiently as possible.

> Sending materials to Earth will cost as much as sending them into space, as the materials must land safely and be recovered as efficiently as possible.

that's not true because the journey from space to earth has an aerobrake option, but the journey up requires a rocket with a certain amount of energy per kg you want to send.

In a large scale operation I think you could send stuff down relatively cheaply. A lot of effort would go into making a really mass-efficient reentry vehicle.

Another thing that would probably end up happening is a reentry bolo - a spinning tether that would subtract a huge amount of velocity from things going down.