The top level: your own device, a personal protected perimeter, a full record of the person in immutable storage. For those who need a guarantee rather than a service.
Everything the other levels do not have.
A separate node in your hands, not a share of a common one. The keys never leave it.
An isolated environment. Your data does not sit next to anyone else’s, not even at the storage level.
An immutable blockchain entry: it existed, it is genuine, it is dated.
Honestly: not everyone.
When it matters that children can ask — and get an answer in your words, not someone else’s reconstruction.
Doctors, lawyers, anyone whose correspondence must never sit in shared storage under any circumstances.
When the work will outlive you, and how decisions were made matters more than the decisions themselves.