I self-host. And then I backup everything to my RAID6 NAS. And then, though irregularly, backup to offline media.

I sometimes read comments on this very forum, that hosting your own email server is risky and requires lots of work. I agree it's not for everyone - you need to have some knowledge of how to run and secure your service on the internet. I self-host since roughly 2011-2012 and cannot say I spent tons of time on it.

It does cost some money though, I pay $5 monthly to run my Nanode (on Linode), and then something around $30 a year to keep my domain.