I owned and ran my own email domain for a long time. Initially on my own hardware for fun, then a VPS, then GSuite, then Fastmail. That's over around 20 years.
So, it wasn't planned - it evolved. Somewhere in the Fastmail era I was reading their docs around wildcarding and thought I'd try it out.
My primary domain is my name though, so for extra privacy (anality) I bought another that has no link to me in the name.
There are still gaps in it. e.g. any merchant site still needs my physical address, and plenty need my cell number. But, generally, it's just an attempt to minimize a digital footprint and see what privacy I can get.
That and just why not? I self-host enough stuff, that I see this as another aspect of the same mentality - having a little more control.
It's not perfect security, it's not completely clean. Hopefully it's enough to get me out of the easy target bucket though.