"but who else is going to use it"
Uh, gamers ?
Let me check the folder size for some of my favorite games :
Battlefield 2 takes 9.9GB
Crysis Warhead takes 3.7GB
Freelancer takes 4.1GB
Hellgate London takes 6.8GB
Lord of the Rings Online takes 12.9GB
Starcraft II takes 8.7GB
Company of Heroes takes 3.9GB
and my Steam folder, with dozens of games, takes up 95.5GB.
Sure, this only takes 145GB in all. You might think that a 250GB disk should be amply enough. Yes it would - for now. But neither you nor I know what games I will add to my collection in the future, and I'll be darned if I want to start worrying about disc space again like I had to ten years ago (when game size on disk was counted in MB, not GB).
I bought a 1.5TB disk for the express purpose of installing my games on it. Yes, I have more than 1.2TB available on it, but that means I have space to install a lot more games. More importantly, it means that defragging is not an issue, and the disk can manage its sectors without problem either. Plus, I have peace of mind and room to grow.
Finally, the disk only cost me 89€. Hey, that's the price I paid for 320GB back in 2007 !