Using your own domain has the same problem. If you ever stop paying for that domain, or lose it for some other reason, someone else could purchase it and start impersonating your email.
If someone takes over a domain they can also get https certificates, reset all their passwords and do all kinds of other things that are related to it if there's no second factor. That's just what you have to accept if you don't renew a domain.
If paying for it is a problem, then pay it in advance for 10 years and setup automatic renewal. Also leave a digital will. You probably want to do that anyway.