These calculations don't make sense unless you really consider TCO over any appreciable amount of time.

It's easy to say you can buy a huge server for a few thousand but the "cloud" provides incredible agility, security, and basically removes operational overhead. When compared to buying, maintaining, and decommissioning servers and software along with the time and personnel costs, it becomes a much closer race. Include global scale, elastic capacity, managed services, and support policies, and it's closer still.

Rarely are companies paying 3x IT spend just to run in the cloud, especially for large companies like Etsy.