[spullara]

Over that time, you could populate a good portion of nearby systems. It would only take 1m years for humans to populate every possible planet in the galaxy:

https://www.learnastronomyhq.com/articles/how-long-would-it-...

Plenty of room for a very large economy. The next galaxy would take some doing though since it is 2.5 million ly away.

[Robotbeat]

Sure, but then your economy is still constrained to grow at the speed of light. A shell of some thickness expanding at the speed of light. The volume of that shell increases parabolically, not exponentially.

So it still needs to slow down growth, although growth can still occur indefinitely. Well, billions of years until stars naturally start burning out, in which case you get a slowing of growth and degrowth until you're huddled around red dwarfs for a trillion or so years and then harvesting energy from black holes until like a quadrillion years.

[onion2k]

"only a million years" seems like a slightly flippant statement in light of the fact humans have only had about 5000 years of civilisation so far.

[spullara]

After it starts it would hard to stop because of the separation except by some other group of similar creatures.