Sure, but we're addressing people who are so far on the other end of the spectrum they're using a "serverless" database where they pay for the number of rows scanned per query. I think a managed DB is a better middle-ground for their capability level while still delivering massive cost-savings.
Amazon RDS lowest-tier runs about $13/mo for 10GB storage, 2 vCPUs and 1GB memory with automated backups and push-button restoring. And that would have likely met all of their needs with capacity to spare.
The time spent setting it up and managing it and then having to deal with backups/environment clones/access control/scaling limitations/etc. outweighs the savings for almost any company paying US wages. Especially since you'd need metal for everything and not just the db due to network latency.
It's very easy to do it in a half-assed way and much harder to do it at scale in a production environment with many developers without hurting developer productivity at all.
Every cloud-hosted startup I've consulted for had a full-time devops guy wrangling Terraform and YAML files. The cloud requires an equivalent time investment.
Bare metal requires the equivalent of all of that devops stuff and then more. That is if you actually want parity and not just a half assed version that hurts developer productivity and causes technical debt.
Amazon RDS lowest-tier runs about $13/mo for 10GB storage, 2 vCPUs and 1GB memory with automated backups and push-button restoring. And that would have likely met all of their needs with capacity to spare.