• easy to use with multiple people
• easier to manage for multiple people
• easier to backup (since you don't need to do backups per device)
• less hassle when you switch personal devices (or reinstall a laptop for ex.)
• You own your data (instead of a mega corp.)
• Less dependent on internet connectivity*, power outages*
• Its a nice challenge
• Its fun (some of us like the self inflicted pain that comes along with it ^sometimes)

*limited to outside factors like how much you actually self host and how much backup power you can store/generate.

Maybe look into this: r/selfhosted/comments/1804cr2/pomerium_v024_update/