I'd rather trust myself.

If you walk around all day with your wallet in your pocket, it might fall out and you'll lose it. Would you like me to hold onto it for you to make sure that doesn't happen?

I agree with you and other selfhosting fans in spirit, I really do.

On the other hand, it's email. I was at a hospital to do a blood draw, and needed them to receive an email (insurance info). I sent them an email from my Gmail. We wait 4-5 minutes. I notice they're checking an office 365 outlook. So, I re-send the same message from my @outlook.com email. Arrives instantly.

Deliverability between MS and GOOG is normally really good, and even that wasn't working right that day. My self-hosted email server being able to deliver to them reliably every time is hopeless. "Big Email" has made it excruciatingly painful to not be on sending from one of their platforms, unless you're one of the big 5 or whatever platforms that send bulk email or bulk transactional email. The SendGrids, Amazon SES, etc.

There's a difference between controlling the domain and self-hosting. You can still use Gmail and Outlook (I assume, I don't know for a fact) with a custom domain. But the difference is if any of those services become less reliable or whatever, you can move your email across to another provider. You can't do that if you're stuck on an @outlook.com address.

But also, even if you're self hosting on a server in your basement, you can still use SES to deliver your mail. Delivery is not an issue here.

The reason we happily walk around with our wallets is because Big Finance and Big Government are willing to invalidate and reissue our credit cards and identity documents, maybe even help us out with the fraudulent transactions after it was stolen.