You're also forgetting that if you set up something on your own you also have all the hardware concerns as well. You need to procure hosts, provision them properly, deploy them, monitor them, scale them, fix them. That infrastructure cost doesn't go to zero but it is significantly reduced using a cloud provider.
I'm not arguing against cloud platforms in general; just the irrational use of very specialized services they offer. I can run a containerized service that uses open source packages on any of the cloud computing platforms. Now if I used Athena, SQS/SNS, DynamoDB, ELB, Lambda, EC2 that would make me very nervous, and I see other devs designing these stacks all the time. I guess I shouldn't care as much, because I'm not going to be the one to migrate that when the company gets a better deal from another platform service.
