Everybody should own at least one domain, it does not matter if you blog or not, it does not matter if you host something or not, but everybody should own a domain at least for one thing, and one thing only. Everybody should have an email address at a domain you own.
We sign up at so many services with our email addresses, Spotify, Netflix, LinkedIn, etc. even our banks use our email address to send us information so we really need to own that email address.
If we were using hotmail.com, gmail.com or even fastmail.com domains to sign up, they are the real owners of our accounts, Microsoft, Google or Fastmail may shut down those services and we will lose control of all other accounts in case of the need to recover a password, so get a TFA token at the email.
There has been a lot of posts about privacy concerns when using gmail or any other free email service, but I think this one is even more important to own your email domain, if you do not care about privacy because you have nothing to hide you may use those services with a custom domain you can do it with Google, Microsoft 365 or other, the best option might be to host your own email server but if you can’t or do not want to, you should use your domain.
Make a list of all services you have to sign using an email address at a domain you do not own, and try to switch them to an owned email, one that is at your domain.