Because they want to play the game and don't know or care what a "kernel-level anticheat which acts as a rootkit" is. Which probably makes up 99.9% of their userbase.
FYI, it works on Linux, so as far as I'm aware, it only seems to care about you flying around.
It's almost 2026, you're supposed to keep gaming and personal PCs separate.
Why on earth is any self-respecting person installing this on their machine?