[Legogris]

a) I'd advice to start with something fun. Many people do a usenet/torrent stack (jellyfin/plex, radarr, sonarr, jackett, transmission, ombi, NZB*, etc). And honestly most things you'd want to self-host are reasonable to run in containers. E-mail. Huginn. Cryptocurrency node. CalDAV, file hosting (Nextcloud?). Personal web site and whatever side-projects you have. GitLab. Docker image repository.

b) IMO, self-hosting and less centralization of the digital services we rely on is highly desirable for society. (If k8s is the right solution for any particular individual to orchestrate their stuff is a different story). I think for most people who do this, it's a hobby and something they enjoy. Why would you have a vegetable patch when there's food in the store and your employer has a complementary lunch cafeteria?

Hackers gonna hack, you know.