If we are only considering traffic then sure AWS can be expensive. Costs me $730 for 17TB of data at the moment. But looking at where money is being saved. 6 ec2 instances previously was $648.24/m, now its $6.82/m after moving to Step Functions / Lambda's, and it just works better as there's no fighting for resources anymore.

You know whats expensive in AWS. S3 Storage. Got some odd ~500TB stored in there. But at 6k/m I can't imagine trying to keep that in dedicated hardware. Atleast in S3 I feel it's safe.