(a) built their own transaction/caching/replication layer using Blockchain no less.
(b) paid SQLite team to add a number of custom modifications.
(c) used expensive, custom, non-ephemeral hardware.
Now you could do all of this or just use an off the shelf database that you aren't having to write custom code to use and if you choose a distributed one e.g. Cassandra will be able to run on cheap, ephemeral hardware.
(a) They implemented a very boring transaction/caching/replication layer that is like any other DB except they borrowed the idea that "longest chain" should be used for conflict resolution.
(b) They worked with upstream to get a few patches that were unique to their use-case. Once you're in deep with any DB this really isn't that uncommon.
(c) They used a dedicated (lol non-ephemeral) white-box server that has a lower amortized cost than EC2.
(d) Bedrock isn't bound to the hardware. You could run it on EC2 and reap the benefits just the same except you'd pay more.
1U of cohost with 100mbps in a cheap Eastern European DC will cost a few hundred euro per month... and my info is a few years old. It's more expensive now.
It is very specific case, that we should not extrapolate to mean it's general use case.
AWS/GCP/Azure are still a better places to start for most people.
Handwaving this layer away as "very boring" isn't exactly fair, either. What does boring even mean here? I mean, this layer solves problems that are both essential to performance scaling of RDBMS and have been proven time and again to be hard to reliably solve in a general case. And it has furthermore been built from the ground up tailored towards the specific needs/use cases of the company.
By the aforementioned handwaving the presented successes are implicitly attributed to SQLite to a degree that isn't justified IMO.