Wow, these are some serious expenses!
I run a service that does ~30 million requests a month, and I only spend $15 on it. It's an apples to orange comparison, but looking at their costs breakdown, I'm sure a couple engineers with a couple weeks can dramatically reduce their costs.
For me, the biggest cost savings were at browser caching. With `immutable` and far future cache expiration dates, webp images, etc, I could pull of the 30m and growing stats without the server load going more than 0.40.