I'll give my own nerdy answer, besides the "good for amateurs" one.

Personally, I'm pretty techy, but I use my PC primarily as a living room gaming PC. As such, keeping it working is paramount, although I can't resist tinkering with it anyway. I was afraid an immutable OS would limit my tinker projects, but I've found it to be a total non-issue. Even for complex tasks like self-hosting AI to play around with, podman has served admirably. Honestly, it gives me confidence to try more ballsy things than I would otherwise, rather than limiting me.

Additionally, I like the feeling that my core system is essentially unbreakable. Even if I ran sudo rm -rf, I don't even have the ability to truly pooch things. Similar deal for any virus or hacker that might access my hardware, you can't hide weird behaviour deep in my system, it's immutable. I've also crashed my computer a few times by blowing through my VRAM budget while tinkering with self-hosting AI, and such crashes don't scare me, I've got easy rollbacks if I crashed my PC while it was doing something delicate.

I'm even running the testing branch right now (I want earlier access to the latest Mesa, as it has bugfixes for the DOOM DLC), and I don't have to fear anything from an unstable branch. If it breaks, I can trivially rollback and switch branches to the latest stable in a few minutes, with immense confidence.

I love the assurance it gives, and the only thing it's ever blocked me from doing was installing my VPN client, but an OpenVPN config has done that job just fine. I'd consider switching to CachyOS, but the main reason I haven't is that I'd miss the comfort of my OS being immutable.