Many people complain about AWS' networking costs, but I also suspect these are generally at-cost. A typical AWS region has terabits upon terabits of nano-second scale latency fiber ran between its AZs and out to the wider internet. Networking is an exponential problem; AWS doesn't overcharge for egress, they just simply haven't invested in building a solution that sacrifices quality for cost.
Amazon really does not have a history of throwing huge margins on raw compute resources. What Amazon does is build valuable software and services around those raw resources, then put huge margins on those products. EC2 and S3 are likely very close to 0% margin; but DynamoDB, EFS, Lambda, etc are much higher margin. I've found AWS Transfer for SFTP [1] to be the most egregious and actually exploitative example of this; it effectively puts an SFTP gateway in front of an S3 bucket, and they'll charge you $216/month + egress AND ingress at ~150% the standard egress rate for that benefit (SFTP layers additional egress charges on-top-of the standard AWS transfer rates).