Things in bold for speed.
1 - I upgraded before the 8700k was released, at the time, a nice 8 core was a 'psychological' boost over my old 6 core.
2 - The 8700k, which wasn't out, was pushed out at a lower Intel price point (had I been able to see into the future and see Intel's post Ryzen pricing restructure, I may not have gone with Ryzen).
3 - The Intel tendency to ditch motherboard for new chips was a factor to me. I can upgrade to the next Ryzen mArch change and keep the motherboard.
4 - My Ryzen was a sideways upgrade, willing to experiment with a new tech arrival, you know, like tech enthusiasts like to do.
5 - I own a 1080ti. Going by your logic of not being able to explain putting a Ryzen in a gaming rig, I can't explain why anybody would buy a Vega 56 or 64.
6 - I gamed at 1440p till last week when I then went 4k. Intel has nothing exceptional to offer me over Ryzen.
Point 4 is the most delicate point. Buying the fastest thing doesn't make it interesting. I enjoyed my Ryzen build. And again, when I bought it, the 8700K wasn't in existence.