Same reason people pay for windows instead of using Linux for gaming. You can accomplish the same task on both but one has more support and is more mature.
Plex has more quality of life features than jellyfin. And for most, that is worth the cost and closed source nature of Plex.
If you’re happy with jellyfin there is no need to switch. Especially to free Plex.
It is generally cheaper to pay for hosting if that’s all you’re doing.
You don’t need a GPU to host a server, just a decent cpu and a decent amount of RAM.
I’m not sure how well it works hosting on the same pc as you’re gaming on. I’d expect it would lower performance for both to some degree.
You can use a power calculator to get a rough estimate of the costs.
For example, a pc running 24 hours a day at 0.30/kwh using 150w would cost just under 30 per month.
You are absolutely, categorically not allowed to use Plex or jellyfin or any other media streaming app on cloudflare tunnels unless you are a paid customer hosting your media in cloudflare R2.
Technically I don’t think you’re even allowed to host something like Immich u less your images are stored on R2.
That being said, I haven’t yet heard of anyone having their account banned for doing so.
You should put a smart plug on your remote server with the bios setting to always power on after power loss.
This won’t help you if you’ve fucked up network settings, but it’s a life saver if your computer locks up or doesn’t come back.
Turn off the smart switch, wait a few seconds and turn it back on again, your computer should start back up.