I have like 1.5 TB on my computer and honestly only play like 6 games regularly with 2 of them being new-ish releases, I can't imagine what I'd do with 9 TB

i think the amount depends on the game count you are used to keeping active . say 20 games x75GB = 1500GB . Not even close to 8TB . But if you want 8TB ,ok . it d be fun

4.25tb total in my rig.....half is empty.....i have a 2tb gen 4, 1tb gen3 and 1.25tb total on 2 512gb and a single 250gb sata based SSD.......

real world a 512gb M.2 gen 3 for the OS and a 2tb gen 4 for the games would be the sweet spot....windows only read and writes at 1100mb a second do to being extended 32bit.....(yes it can run 64bit coding at faster speeds but the OS itself is limited to these speeds)

I recall back in early 80's the 10mb hdd, (yes, MB's) appeared and one scientist guy stated that no-one would ever have enough data to fill a drive that big in their lifetime.

Well, I'm still around and filled it a long time ago.... now i have several tb's .....

So, back to question, how much is overkill ?

It's only overkill if you can no longer remember what you have on it. Regardless if it's 1 MB or 100 TB. Once you reach the stage, that your drive looks like your garage or storage unit.. .. seek help.

The pirates have storage issues . They store install files along with installations . Non pirates have download servers at their disposal . i had installed 2TB +2TB disks . one was 75% filled the second - 4% lol . i mean Steam users dont need much local storage

9tb is certainly a lot. Modern AAA games are usually around 50–150GB per game. Games with 4K texture packs rarely exceed 200GB. With 9TB, you can store dozens to even hundreds of games without having to uninstall anything.

5TB full because i do gopro videos, i can install my whole steam library with ~2 TB of storage left otherwise though

Depends, I'm gobbling up 6 TB in games right now, probably gonna go 2x4TB in raid0.

I've got 12GB in SSD storage (both SATA and NVMe M.2 drives) and a WD Black 6TB SATA HDD, so that a total of 18GB for games, and due to my owning 100's of games from Steam, EGS, GOG, and even Windows games, I've filled up about 40% of my toal storage space.

There is a good number of games I've chosen to NOT install (mainly because I've grown tired of them, or games that I'd pre-ordered and regretted - like Alan Wake II which I can name right off the top of my head)

引用自 Shadow-79：

A single game doesn't even exceed or reach 1TB, the highest ones are around 125GB (usually a collection of multiple games can reach 1TB SSD full capacity). For example, if I had a gaming laptop with 1TB + 8TB SSD installed inside the hardware even with the computer having RTX 5080 (GPU), is that sufficient for both long term storage and performance (4K textures or resolution).

No have as much as you wish.

my preference would be a hard drive with a small SSD. Either move games around or use something like primocache.

I have a tonne of storage for Old Arcade MAME sets, running NAOMI and SEGA AM2 systems.
Scratch space for any creative work since I use Corel studio software, music making software and do some video editing. And a dedicated SSD to a Linux O/S.

I have 11TB total.

never hurts to have too much storage
I have 3x2TB nvme and 2x 1tb sata ssds
and considering to replace them with 4TB, when or if ssd prices stabilizes...

for just games? yeah it can be overkill but it is nice having everything installed at once
plus enough room for clips.

Is it overkill? Depends on the needs. But needs and wants are different things and to each person, a different solution.
I only disagree with the "long term storage". I actually prefer to have a small amount of storage, forcing me to not have any "long term storage" on my drives. I haven't trusted a single computer drive for long term storage for decades. My last 2 phones I didn't even bother to "copy" anything to the new phone, I have permanent backups in place. Same with my computers. All I need is to reinstall stuff, login to the cloud server and voilà. I have everything again. Music is cloud, movies and TV same, games ditto...
I have 1.5TB. Don't play that many games at once, so I can just uninstall something and install again later. Even better since most are from Steam so I get to keep my savegames.
Yes, it's a pain if a drive dies and I have to do to legwork, but I lose absolutely nothing. I don't even do "backups" of the system. I just got used to copy everything important to the cloud service. Before that, got my first CD recorder in the 90s, after working a few months while finishing high school. And have always copied important files to media.