system
Given the following post, respond as if you're commenting on Reddit:
human
[40k] Is Chaos corruption alone enough to bring Chaos Space Marine creation up to replacement levels?

Or are Chaos Space Marine numbers being slowly depleted as the original traitor legions die or turn to Chaos Spawn?
gpt
The numbers of the original traitors are being slowly whittled down - although not as quickly as you might expect, since some of them get resurrected due to Warp fuckery.

However, they're also always recruiting. They still have gene-seed, and armies of cultists who would cheerfully volunteer to have it implanted into them. Fabius Bile is constantly performing perverted experiments to make new Chaos Marines.

On top of that, the Heresy was the biggest incident of Astartes falling to chaos, but it was far from the only one. Few outside of the Grey Knights are completely immune to the temptations of the Ruinous Powers, and it's not unknown for entire Chapters to fall to Chaos (most famously the Astral Claws/Red Corsairs, under Lugft Huron/Huron Blackheart, the Tyrant of Badab).