system
Given the following post, respond as if you're commenting on Reddit:
human
(WH40k) Why do space marines die so often?

Reading through many of the records of their exploits it seems like they die a lot more often than their apparent toughness and skill should allow.
gpt
Space Marines are our desperate attempt to get to a MINIMUM level of survivability against the horrors found in the black.  Compared to the brave men and women of the Imperial Guard, who sacrifice their lives by the THOUSANDS to hold ground, the Space Marines are incredibly mighty but compared to the abominations of the Warp they're just barely on an even footing, and they're typically MASSIVELY outnumbered by xenos that breed or corrupt others with nightmarish speed.