Inexhaustive of things that kernel mode code can do that unprivileged (without “root”) user mode cannot:
Update and install drivers.
Run programs (like cryptominers) without them appearing in the task list.
Make network requests ignoring all firewalls and monitoring tools, even when seemingly in airplane mode.
Monitor your webcam and microphone, possibly without turning on that little light next to it.
Escape any sandbox you put it in.
Replace the OS with one containing malicious code.
Replace the efi firmware with one that replaces any future OS install with the aforementioned malicious OS.
Permanently brick your graphics card.
Take advantage of buggy hardware to burn your house down.
And so on. The question you should be asking isn’t “are they going to do this?” but instead “why are they even asking for this permission in the first place?”.
A game where you run around pretending to be a space marine doesn’t need low level access to your hardware.