I feel like step 1 is just buying a domain so you can have control over your e-mail address, and then you can switch providers whenever you want (or host it yourself).

If you already pay for extra iCloud storage you can use a custom domain for e-mail with iCloud… Many people are already paying for this, and if not it’s only $1/mo. Apple’s still a pretty big e-mail provider, so maybe that doesn’t address all of your concerns, but it’s a really cheap way to use a custom domain that more people should take advantage of imo.

I host my own e-mail and it’s pretty care free these days (I don’t send bulk e-mails, though, so I don’t contend with rate limits at all). Honestly, more people should do it instead of buying into all of the fearmongering about e-mail… It’s a little tricky to set up right, but the impossibleness of the situation is somewhat exaggerated. The best defense for self-hosted e-mail is if more people actually do it… Otherwise you’re just capitulating to the large (and slightly less large) mail providers.