No one is going to run a database for you unless you pay them. If you want to write data to an existing public ledger, then you are going to have to get some of the token that allows you to write to that ledger. Paying for a token to use the ledger is not speculative, it's pragmatic. Holding the token and not using it to write to the ledger is speculative, and encouraging people to do that in order to make money yourself is a scam.

If you pay AWS to host Postgres for you, are you being scammed? You might be if someone convinces you to invest in Postgres credits that you never use. But if you actually use Postgres, and it's cheap, and you are glad to pay for it, then it's not really a scam.

I think more of the promise of these technologies is in private ledgers, where the traffic is confined and the system could even be run altruistically. For example, a university club or a town could coordinate elections using this technology. They don't have to pay to use a public ledger if enough people in the group can run nodes themselves. Everyone who cares about the result of the election is incentivized to participate in the network just to know the result and ensure its authenticity. They aren't processing transactions for random users, they are coordinating using the latest technology with people who they want to coordinate with.