Another perspective. You got lucky that the dependencies you're working with haven't gotten as bad as the ones for Gmail and the like. Sure you've got a domain, but you've also got a domain registrar you're dependent on. Yeah, you've got your own email server, but it's dependent on open source software, and the monopolists allowing it to still connection, though that's getting iffy. You're also dependent on the kindness of a number of people continuing to contribute to Linux, and it not being compromised in some way.
I made a different choice 25 years ago, and went with Gmail, but the idea that you're smarter because your dependencies didn't turn to sh*t is as much luck as skill. 25 years is several eternities in tech, and there are no guaranteed outcomes.