system
Given the following post, respond as if you're commenting on Reddit:
human
[mass effect] Why do the reapers do what they do?

We know they come back from deep space after every so long through the mass relays and they fuck shut up with their lasers, but why do they do it? What is their overall goal? Do they do it for fun or is it something else? Could it be that they keep going through the cycle until they can find a species/group of species powerful enough to take control of the galaxy?
gpt
Their leader explained this pretty clearly. They can't allow advanced species to go extinct by the hands of their own AI, they were created specifically to keep that from happening.

So they prevent this outcome by taking that species and forming it into a new Reaper. This preserves the species, from their point of view.