system
Given the following post, respond as if you're commenting on Reddit:
human
[Stellaris] Why do the old empires not expand ?

Just why? They are supierior to me and the other spacefaring empires in every way. I am capable of conquering the entire galaxy in around 250 years and they are just sitting ther doing nothing.
Just what (or who ?) did bring them to stop expanding?
gpt
They didn't stop. At least, not all of them. Just like your fledgling civilization, they once hoped to bring their dominion to the whole of the galaxy. Some expanded far too fast and fell on in-fighting, or turned to other pursuits once they had enough raw materials. Still others accomplished their goal of conquest, but ascended to higher planes of existence.

What you see are the remnants of a once-great empire. We retain the technology which served us, but do not retain the delusions of grandeur. There are more important, dangerous and even sinister things in this galaxy to worry about.