What I said was that for the functionality pinboard provides, and the number of users using it, the hosting costs are extremely high.
If the hosting costs are high because of inefficient software, or bad architecture decisions, then those should be changed.
If anyone here believes this, make your best estimate as to how many man-months you need for a re-architecture and how many hundreds of dollars you'll save in hosting costs, then do the division to get your effective hourly rate. I'll pay you that plus 50% for contract programming work.
For $21.6k/yr I'd say it's worth a week or two re-architecting.
Yes, it's a different game if you're profitable and $21.6k is negligible, but if you're a startup you should be spending time to optimize things.
The other point is one of scaling. If you're paying $2k/mo to support 15k users, when you scale to 15m users, you could be paying $2m/mo unless you fix things early on.
It looks an order of magnitude too expensive to us, there's probably some simple thing wrong in the architecture.
Maybe we're all missing a key complexity of the service. The Archival service might be it.
As for high hosting bills, build your own equivalent version and then share your own hosting bill data.
Still, easy to criticize without knowing the full facts...