That's a general answer on how you can save by using the cloud, I specifically meant the "serverless" variant.
(Apart from that, I think this is a misconception - Amazon seems to have convinced people you don't need a sysadmin anymore, whereas in fact once you start exploring the whole AWS infrastructure and its complexity, you quickly realize you still need sysadmin's knowledge plus understanding of how their services work and all their quirks.)
I understand that with AWS, you need a sysadmin. That is why I was saying with serverless (in this case, AWS Lambda) you didn't need a sysadmin. I assume it's the same with Google Functions and whatever Azure has.
But you will need other things... you need some kind of fronting system to tie things together, you need some sort of DB/Storage. And while you can get away with fewer admins, someone will be spending part of their time in a sysadmin role. It's more a matter of how much can get done with how many admins.
I get the point you are trying to make, but as AWS offers many services, I don't need a sysadmin for a DB (RDS, Dynamodb, ElasticSearch, S3) or for APIGateway nor for any coordination between systems (SNS, SES)
True serverless let's me offload that cost to AWS instead of having a sysadmin
Who maintains the database, schema, updates? Application deployments, testing, qa, updates? There's someone doing the job, even if it's fewer people, or someone with multiple hats.
(Apart from that, I think this is a misconception - Amazon seems to have convinced people you don't need a sysadmin anymore, whereas in fact once you start exploring the whole AWS infrastructure and its complexity, you quickly realize you still need sysadmin's knowledge plus understanding of how their services work and all their quirks.)