There is a Ninth Circuit decision that domain names are a form of property

https://en.wikipedia.org/wiki/Kremen_v._Cohen

but it's tricky because the domain name registries and registrars have a kind of thicket of contracts nowadays that subordinates registrants' property interests to other rules and considerations. So I don't think a court would think that a modern-day domain name registrant has property rights in a domain name that supersede all of those contractual terms.

Edit: my recollection is that Kremen v. Cohen interpreted the legal defaults that applied because Kremen registered the domain name in an era when Network Solutions didn't require registrants to agree to a contract that limited Network Solutions's liability and gave it various explicit rights and powers.

I'm not a huge ICANN expert, but I think ICANN broadly thinks the status quo is preferable to one in which registrants had stronger, less equivocal property interests in names.

Agreed, but I just wanted to say that essentially every single thing anyone owns is, and has been from the invention of tally marks on clay tablets, an entry in someone's ledger.

These domains wouldn't be worth a penny if they came with a disclaimer that they can be deregistered or even taken over at any point. With a bit of luck, somebody could snatch popular last name domains and set up a catch-all mailserver.

Everywhere.

Well anyone can buy a second.name if second isn't already registered, and then set up their own first. subdomain, so most visitors aren't going to know the difference in between grandfathered in first.second.name sites and people who just bought second level domains and created their own subdomain.

if you're lucky, you can do something like first.sec.ond

works for many polish people who own ski resorts :)