It's a little bit of both for me.

I do host things for fun. Otherwise I wouldn't be running my own instances for Lemmy and for Mastodon. I don't need to host services like an IPFS Podcasting node or a PeerTube relay server for Jupiter Broadcasting, but I like giving back to the podcasting community (and theirs in particular, mostly).

Other things could fall into both categories but are a significant improvement on my Quality of Life. Automations fired by Home Assistant make it so things like my bedroom being warm during the winter is possible without having to remember to preheat it before I sleep. Services like AdGuard Home and PiHole help me control segments of my network and prevent ads and other malicious sites from being opened on my LAN. Hosting my own password manager through Vaultwarden and my file and photo syncs through a combination of NextCloud and Syncthing, though it has availability drawbacks should my server ever crash, lets me maintain more control over my data than I otherwise could have.

Plenty of other things are nice-to-haves and not need-to-haves, but they're worth spinning up to try out and see if they fit into my lifestyle. If I didn't enjoy self-hosting, I wouldn't have started to do it in the first place.