I see paid relays as a stop-gap measure to try to prevent spam. I run nostr:npub16fcy8ynknssdv7s487nh4p2h4vr3aun64lpfea45d7h4sts9jheqevshgh as a non-profit to ensure there is no need for sponsorships. Have applied for grants and get some donations to cover costs. The big issue with relays is I see many are literally just one server (single point of failure). As well as being siloed, so if a big relay goes offline a huge chunk of nostr will as well. Promoting streaming between relays and clear ToS/Privacy Policies and how data is managed is key to #grownostr . I have posted a lot on this but few relay operators engage in the discussion.
Discussion
It's not about spam. It's about incentives. They will have to find money somewhere to pay for servers.
Seems like paid encrypted DM image hosting could subsidize the free services relays provide?
nostr:note19zqrrs38pw88dl3r6t6tmqfam5kd6zlx7dppz47kxwmk3mxnwefq9x4tmc
Could relays be free and paid at the same time? Accept notes of a certain size freely but come back asking for payment of LN invoice to accept notes containing more data than their set threshold?
It's possible, but data storage is the cheapest part of hosting a relay. The actual instance (compute) is usually the most expensive part. If right size everything and leverage Docker containers can keep costs down for a very robust network like we have. Of course the more data the more processing so have to take into account.
I see monthly paid relays as possible but most with one time is not sustainable. Some popular paid relays are black boxes which is hard to know what paying for.