system
Given the following post, respond as if you're commenting on Reddit:
human
[Mass Effect] Sustainability of the Reaper threat.

So, each cycle, the most important civilization is turned to goo to form a reaper, the rest are just killed or turned into troops. Last Cycle it was the race of Prothean Javik was, this cycle it was the humans. 

because Shepard killed Sovereign, The Reaper coming in through the Batarian Relay, the Human Reaper, The Reaper on Tuchanka, The Reaper leading the geth, plus an unknown number on the fight at Earth, that’s at least a net loss of 4 Reapers, and they only made 1 during the present cycle which Shepard also killed

How have the Reapers been able to sustain themselves as the omnipotent threat since with minimal preparation, they could eventually be rendered extinct via a war of attrition?
gpt
In their efforts to preserve a galactic record of life, the reapers built new reapers out of the remains of each cycle's significant civilizations. However, this does not mean that is the only reaper constructed. Little is known about what the reapers do while in deep space, and it is entirely likely that even during hibernation, their bodies are busy constructing new bodies to contain their selves.

Additionally, reaper purges of the galaxy typically lasted hundreds or thousands of years. There would be plenty of time to create and supply fresh troops from the remains of the civilizations they had effectively assimilated (in a manner of speaking).