If you increased your usage metrics by 10, 100, 1000 what does that do to costs? How many users or messages an hour would make it untenable for you to keep hosting?
To be honest I'm not sure off the top of my head, lambda/dynamo/s3/iot scale quite a bit. Opensearch is one of the most costly services but I have it behind apigateway cache.
I'm sure those services can scale but what I wonder about is if the cost of scaling will become prohibitive. If your posts per day increase by three orders of magnitude will your costs?
