I think you are confused. I self-host a ton of stuff. One thing I have zero interest in is hosting mail and dealing with all of the configuration and possible timebombs waiting before I can even do the single thing I want the service to do. Instead I pay like $5/month for essentially unlimited emails from any domain I control.

That said, none of it has to do with my own personal email, which has been on Gmail for long enough to drink, so we are probably talking about two different situations.