Let's say you wanted to host email with your own domain for the rest of your life. It's likely at some point you'd lose the domain.
I've had my own domain and been running my own email for almost 30 years (from back in the day you had to pay Network Solutions more than $100/year just for a domain). My current domain provider lets me renew for multiple years, I get plenty of notifications about it expiring, etc.
I can see a case where if something medical happens to me for a long term at the wrong time I could potentially lose it but I don't see why that would apply to most people, that's a very specific instance.
All people get old. The chance of something medical happening in a life is near 100%.