Find a problem they are experiencing and introduce them to a solution they can self-host to fix it. Expand from there.
I began my self-hosting journey 7ish years ago with media piracy and a desire to watch/access my files wherever I was. Learned of Plex, then Emby, Reverse Proxies, Domains, SSL, and on and on…
Today I’m running 24+ docker containers and some miscellaneous stuff, across 3 systems; that’s always accessible via my domain/vpn.
I host my own vpn from home, which keeps me behind my pihole(s) and able to access my private services without exposing them to WAN.
Also secures my mobile traffic from snooping/modifying while on public networks.