I have one single video game I play that takes up around 650GB, so I have a dedicated drive for it. And between 1 and 2 TB of movies, TV, and photos. Everything else is ephemeral/scratch space for whatever I'm working on.
I used to be into amateur movie making and editing, and back then I needed many TB of space for the stuff I pulled off my cameras before it got edited down.
I don't know what it is for GP, but in my case it's Flight Simulator 2020 with over 700 GB. Not the standard installation though: it's community mods, mostly photogrammetric data for additional realism. There's a whole ecosystem around the base game that could easily fill several TB if you go all in.
I used to be into amateur movie making and editing, and back then I needed many TB of space for the stuff I pulled off my cameras before it got edited down.