I’m surprised that relays offer a one time fee. That will never be sustainable.
Protocols are documents. Networks are built by businesses delivering services.
I’m thankful that I have the opportunity to participate in a decentralized social network where I pay the enabling businesses with money and not my personal data.
These businesses have recurring monthly costs so I expect to pay recurring charges.
Those who think that paying a reasonable monthly fee to a few relays is expensive need to do some additional thinking on the trade offs of centralized social media.