Scam? You mostly get what you pay for.
Sure, it cost me £6/mo to serve ONE lambda on AWS (and perhaps 500 requests per month). Sure it was awesome and "proper". But crazy expensive.
I host it now (and 5 similar things) for free on Cloudflare.
But if you need what AWS provides, you'll get that. And that means sometimes it's not the most cost-effective place.
On the other hand, we have dozens production workloads on Lambda handling thousands of requests daily and we spend like $50/mo on Lambda.
I'm really intrigued by what you did to get to those figures!