hey maybe avoid the patronizing crap? I've been involved in running at-scale properties in the cloud and not for 20 years or so now so, whilst i dont know everything i do somewhat know what im talking about.

Making an RDS postgres instance multi-az with automatic failover, and bulletproof backups to s3 is ticking a couple of boxes. Compared to building all of that yourself at the same level of uptime - its not complexity of the same magnitude at all. And sure it will cost you more for the instances for redundancy, but its pretty easily worth it - i dont have to pay an ops team to babysit my databases. Thats just postgres - not even getting into things like aurora, dynamo, kinesis, sqs, lambda - things that either dont have a self-hosted equivalent at all, or if they do are way more complicated to run at scale than PG.

In some cases its trading cloud costs for personnel costs. Both opex. But in many others its having access to services, datastores etc that i couldnt otherwise have as a dev.