What profit incentive do people have to run a relay? Most people are not going to pay for relays. You have to know what a relay is and does to even begin considering paying for one. Most people are not going to do that. You can advertise on a client (useless because people will just use a different client) but you can't really advertise on a relay. I suppose you could sell your users data. Plus on top of low financial incentive to run one, it also carries pretty stiff risk. Especially for large public relays. I'm not saying your entirely wrong. But it's going to be a loooong game for nostr to finally win.

I think small, niche, community relays and small special use case relays will be the backbone of the decentralization. For this, relay software has to get a lot easier for anyone to run with with very little technical expertise.