Mining the Sky & Space Tethers to achieve LEO

>
> The earth is fine for earthlings, at least for now, but space
resources are for space inhabinents who can sell weak metals like gold
to earthlings for cash. :-)
>
Depending on the price of transport, you might want to use gold as
wiring in the colonies.

Let put the question out this way.

What is the biggest, most advanced, terrestrial civilization you can
imagine?

Are we near this limit or do we have an extra 1000 years to get to it?

I can argue that we have reached the natural carrying capacity of the
planet. With active effort, we can artificially maintain a higher
carrying capacity on earth. How much effort, and how much higher can
the carrying capacity be artificially raised?

Bill