Ok, now I understand, thanks. My opinion about this topic is that in the future everyone will be able to make clients with pretty little investment (almost zero). If clients become increasingly interoperable over time and everyone can create them, this means everyone has individually the benefits of interoperability BUT that doesn't mean those clients won't come without tradeoffs (see, I'm one of those that think that everything comes with tradeoffs. Also, the more useful or convenient, the more tradeoffs it has)

If everyone has to deal individually (or even in a Dunbar number fashion) with those tradeoffs, that means everyone will have to soften them paying MONEY (summing it up: the fact that everyone can make highly interoperable clients almost for free means they will have a clear DEMAND for the things that make clients smoother). Another thing is that individuals won't be really able to deflect the cost of making clients smooth by passing that responsibility to big corporations because that will be economically inviable in a free market

Everything I said makes me conclude that there will never be free lunch again because clients will be an eternal source of demand for everything Nostr related (Relays, dev work, etc) and the starting point for a sustained division of labor.

So, saying that relays are cost centers is highly gauche