It's important to note that in this case we are only speaking of boot drives, which tend to be smaller than dedicated storage drives, and that is especially true of SSD boot drives. But you could use a 4TB SSD as a C:\ boot drive provided you partitioned it off, which is what I do with my PCIe4 SSD boot drive, a 500GB Samsung 980 Pro--I partition C:\ as ~225 GB and the rest is partitioned under another drive letter. I do it this way because all I keep on C:\ is the OS, utilities, device drivers, and related stuff. Makes it much easier and simpler to use Macrium Reflect to regularly back up C:\ after OS build upgrades, new program and game installs, etc. When I have everything I want on C:\, I've still got ~60GBs free on C:\. Much faster to back up 225GBs as opposed to a C:\ weighing in at a few TBs, and so on. I keep three C:\ incremental OS build backups at all times on a dedicated HDD partition. Works well for my system at home.
Where spinning drives always win is in raw storage, of course. My next data drive will likely be an 8TB + 3.5" drive--as atm I have 5 HDD's and two SSDs totaling about ~8 TB in total--these are HDD drives I've had for a while that I bring with me every time I upgrade. Still running fine, no problems, yet.
My PCie4 Samsung 500GB 980 Pro runs great full bore PCIe4 and I have no overheating problems with it, but I can't say the same for my 250GB PCIe3 Samsung 960 EVO .M2--with the 980 Pro I can do a full Defender AV scan of C:\ running flat out with no troubles, from start to finish. But with the 960 EVO, I cannot finish a full C:\ AV scan before the heat throttles the drive to a full stop! Interesting, because although the 980 Pro sits in the first M2 slot, directly beneath my 6900XT, the 960 EVO is in the second slot with nothing installed on top of it. And, with both drives, I use only the very thin metal "heatsinks" (if you will) that came with the motherboard...! Maybe 500GBs with the 980 Pro, even at PCIe4 speeds, is the sweet spot for that drive--and that little heatsink does fine. But the 960 EVO is even smaller but overheats much faster running at the slower PCIe3 mode.
I can definitely see how PCIe4/5 TB-sized M2 SSDs could require a more pronounced heatsink than what my 980 Pro presently uses! Interesting thread, guys...😉