Earlier quoted context omitted.
Own your own domain, point it to the email hosting provider of your choice, and if something went horribly wrong, switch providers. Domains are cheap; never use an email address that's email-provider-specific. That's orthogonal to whether you host your own email or use a professional service to do it for you.
This is my plan. I will lose some email history, but at least I don’t lose my email future. However, you can’t own a domain, you are just borrowing it. There is still a risk that gets shut down too, but I don’t think it is super common.
I self host my mails but still use a freemail for the contact address for my providers. No chicken and egg problem for me.