This is not only email, but also cryptpad cloud (replace google docs) and XMPP.
Self-hosting XMPP or SimpleX is far more private and secure than relying on a random third party server.

While I agree email isn't that private to begin with, this protects you against passive AI surveillance to a far greater degree.  And email has a big risk of aggregating all information about you.

The real benefit of our product is getting all of these services on a single tiny VPS, so you get the most bang for your buck  

 Yeah I think it's a good idea. I absolutely hate setting up self hosted email, so if I needed to self host I'd definitely rather pay someone to set it all up for me. It's like the best of both worlds: you get the security of self hosted without the pain of having to do it. Bonus points, you get xmpp?

I personally dislike email, but the fact is you're stuck with it, and if you're all about your privacy and security, self hosting is the way to go.