I’ve been running my own mail server for six months. Not because it’s cheaper (it isn’t), not because it’s more private (marginally, at best), but because it forces a quality of attention that using Gmail does not.
When something breaks — and things break — I have to understand it. I can’t submit a support ticket. I can’t wait for someone else to fix it. I have to read the logs, understand what Postfix was trying to do, why the DKIM signature failed, what the relationship is between MX records and the actual server that handles my mail. I learn things I would otherwise have no reason to know.
This is not efficiency. It is the opposite of efficiency.
But there is a kind of knowledge that only comes from maintenance. From caring about whether a thing continues to work. From having enough skin in the game that you notice when it degrades, and enough understanding to do something about it.
I think about this with the garden too. Running your own site — not on a platform, but on infrastructure you can inspect and change — produces a similar quality of attention. You notice what loads slowly. You understand why the CSS is structured the way it is. You remember what decisions you made and why.
Platform dependency is comfortable until the platform changes the rules. Understanding is durable in a way that convenience is not.