We're in the same camp with a cluster ~2x as large for Squawk[1] and it would cost us many multiples in the cloud (excluding our TURN relays which aren't k8s). However, the one killer feature that the cloud still has over self hosted is the state layer. There is nothing that comes close to the turn key, highly available, point in time recoverable database offerings from the cloud providers. We're running Spilo/Patroni helm charts, and we've really tried to break our setup chaos monkey style. But I'll admit I'd sleep better leaving it in Amazon's hands (fortunately, with all the money we save, we have multiple synchronous replicas and ship log files every 10 seconds).

[1] Shamless plug Squawk: Walkie Talkie for Teams - https://www.squawk.to

_EDIT_ I've just read your blog post. We went the other direction and have used the local storage provisioner to create PVCs directly on host storage, and push the replication to the application layer. We run postgres and redis (keydb) with 3 replicas each with at least one in sync replication (where supported) and shipping postgres wal logs to S3 every 10 seconds.