It all depends on what _you_ want to do or need. But since you asked...
I would assume (since you mentioned gaming machine) that this system will (have to) run under Windows. If you don't want to jump through Microsoft's hoops, all programs will have to reside on your boot drive. Add to that that you will always have to download any game from some online service, and your game license will only be useable as long as that online service still exists, I don't see the need for a large drive for gaming.
As for work related stuff - if by "work" you mean "I earn money with it" or "I need it for my education", then I would strongly suggest you investigate the various backup strategies, which then should be an integral part of your hardware setup.
So my suggestion (eventually, what I plan to build q1 2020 - or whenever Intel fnally manages to sell a decent desktop CPU again) would be to have only that 1 TB m.2 SSD in the computer, and your data dump (together with a first level backup) on an external RAID NAS (updated every 14 hours). A second level backup could then be a couple of HDDs in a hot swap cage (updated/swapped once a week), a third level an online backup service.
The advantage of that NAS can be (some systems have that kind of service included) that you can run it not only as a local file server, but also access it from anywhere else. Double edged, for sure.