JaakkoMultanen on Nostr: Holding your own keys isn't really even about technology, but about being able to ...

Holding your own keys isn't really even about technology, but about being able to carry the associated responsibility of having those keys. The majority won't want that.

Some will not be capable, most will not be interested.

As long as there is the backstop of being able to exit, it's perfectly ok for the majority to be on a varying scale of semi-centralized custodial platforms (the more of these the better). This is also the solution for the scaling problem.