To be honest, if you are serious about gaming, an SSD is a must. Playing any graphically intensive (with lots of scenery files, character outfits, weapons, vehicles, etc) whilst running off a HDD, is just asking to ruin your gaming experience. The only games you can really play on a HDD without suffering noticeable lag are more basic games, the likes of minecraft etc, where it's less intensive and there's more of a focus on the CPU, than there is loading gigabytes worth of scenery or game files into the game world.
Games like these are especially bad, because wherever you move across the map, the game has to continually load the world into view.
I currently have a 1TB Intel NVME SSD, and a 500GB Samsung 870 Evo SSD, the latter I bought off Amazon UK for about £55, considering you used to pay that for a 250GB SSD, the prices have come down a lot in the last few years. My system has no mechanical hard drives, they are so outdated and slow by today's standard. Even the best mechanical hard drives can't really compete with an SSD (assuming it's a decent brand), and the other point to note as the SSD is solid flash memory, it has no moving parts, and therefore is less likely to get damaged or stop working in the same way a mechanical hard disk drive (HDD) would.
Just make sure you get a decent brand SSD, and don't cheap out, some SSD's i've used in the past that were cheap were absolute jank, and only slightly better performing than a HDD.
Samsung, Intel, Kingston, WD (Western Digital), SanDisk... all decent brands and should perform absolutely fine.
I plan on getting a Samsung 870 NVME as the next upgrade as well as a full matching RAM kit.