[IYasha]

Provided you're in the same coutry as the registrar and using your passport for registration. And you don't miss your pay date (they usually don't allow to pre-pay for many years in advance). And payment remains available (I once had to resort to paying with cash(!) because of banking troubles). And registrar doesn't get bought, go bankrupt, etc. After losing an important domain I can't say it's THE way to go. Also, self-hosting e-mail is a nightmare. Not only because of ridiculously complex software, but also need to be trusted, which, in e-mail world, is hard as...

[Kuinox]

You don't have to self host your email, you only need to redirect to your preferred email service.

I prepaid my domain name for 15 years.

You can transfert your domain out of a registrar.