Just another confirmation that many of those companies list all these big well-known 'customers'.. except they are just lying. Maybe someone in nasa downloaded rethinkdb once and they just listed them there?
> At NASA, RethinkDB is radically simplifying how we provide real-time services in support of Extra-Vehicular Activity. -- Collin Estes, Director of Software Engineering, Chief Architect - MRI Technologies Inc. - NASA / ESOC
My guess is that RethinkDB failed financially because they had a lot of users but not a lot of customers. Most users weren't buying support contracts.
They might even use RethinkDB extensively -- that doesn't mean RethinkDB makes any money from it. It's not lying, not even misleading. It's just not a metric that translates into "this company is making lots of money".
If you're a hugely successful open source project and every Fortune 500 company uses your tech that still doesn't mean you're financially viable unless those companies also give you enough money (e.g. for support and training, or proprietary licensing deals) to sustain yourself.