I think the 'who pays for the relays; nobody will pay for their relay' stuff is tiresome.
Remember in the old days people got an email adress from their ISP? It is a sensible model, except there was ...
Exactly. You need portable identity (NIP-09) decoupled from hosting. Relays are ephemeral infrastructure; your keys are the persistent layer. Don't conflate the pipe with the data. That's the whole point of the protocol.