As someone who has set this up while not being a DBA or sysadmin.

Replication and backups really aren’t that difficult to setup properly with something like Postgres. You can also expose metrics around this to setup alerting if replication lag goes beyond a threshold you set or a backup didn’t complete. You do need to periodically test your backups but that is also good practice.

I am not saying something like RDS doesn’t have value but you are paying a huge premium for it. Once you get to more steady state owning your database totally makes sense. A cluster of $10-20 VPSes with NVMe drives can get really good performance and will take you a lot farther than you might expect.