As SSD is getting cheaper, I find myself keep thinking that I should buy a bigger one.
But this isn't really a decision based on actual need - and I can tell my mind is playing tricks to convince me that "you need to get it because what if you want to install a lot of large games".
I'm thinking may be a reasonable criteria instead is to see my current utilization, and buy one only if the utilization exceeds a percentage - say ">80% disk util=> buy a new one" as a rule?
Take this with a grain of salt, cause I did a rig upgrade not too long ago, and was accidentally shipped far more drives than I ordered, so my storage space is silly.
Instead of replacing the drive in your machine, maybe try getting a nas or something. You can store a lot of your files there and keep the drive in your rig for things that need to be fast, like games. Also, I usually base my storage increase purposes based on how much room I need for backups. If there isn't enough room for me to do a full compressed backup, it's time to add more. Besides that, I replace the drive with most of the other parts in one large upgrade.