People must put a lot of junk on their OS drive. I know some have said that certain retailers software comes with a lot of bloat, but it can't be that much, surely...
I run a 250GB Samsung 970 Evo NVME as my OS drive and still have over half of the space left. And that's after fully up to date Win 10, Photoshop, Lightroom and many other programs/software. The one thing I have always done is move my Temp files to always be written to a secondary HDD. So I have 250GB = OS, 2TB SSD = Steam/games, 3TB HDD = Storage/music etc, 500GB SSD = Scratch drive.
And what has been mentioned above about SSD/NVME speeds. Honestly there is no real difference between a 500MB/s SSD and 3500MB/s NVME. It's mainly just a sell scam. In real world situations such as gaming you wouldn't notice the difference. And some may argue that transfer speeds are much faster. No they're not. And let's face it, you don't want to be writing to an SSD all the time anyway.