Article doesn't mention any numbers. OVH VPS is $3.50 for a 2GB RAM and 100mbs (about 14TB a month assuming 50% utilization). That is about 14mln pages with 1MB size vs 1mln requests for API Gateway at $3.50, not including Lambda costs or bandwidth costs.
I don't have exact numbers, but we have dozens of lambda functions written in Python which are parsing and acting on Kinesis log streams (at volumes that cause problems for the Splunk ingest), and regularly hit the 100 process concurrency limit... but our bill is well under $10 a year (yes, year, not month. Hence my use of the adjectives "ridiculously" and "stupidly").
Luck? Hidden discounts? Don't know. Just know that our bill is ridiculously low for everything we're doing.