Serving 15 terabytes of 4K video for $2.18

- It's a cornerstone of their brand.

- R2 users are at least paying for something (storage).

- Their network is massively overbuilt to be able to absorb DDoS attacks.

- They offer free bandwidth with their CDN - including completely free users. These resources need to get fetched from origin and/or cached. R2 doesn't have to fetch from origin which eliminates the bandwidth required for the fetch.

Large providers typically pay very little/nothing for bandwidth other than equipment costs (ports, etc). As a large provider they have free peering to most of the "last mile" ISP/eyeball networks in the world. This benefits all parties because these ISPs don't have to pay transit providers and neither does Cloudflare and it's faster. Same goes for all of the big clouds.

People who think AWS/GCP/Azure/etc bandwidth pricing of $0.12/GB (or whatever) is fair/reasonable have no idea what bandwidth actually costs these operators. As noted it's effectively nothing and the big clouds capitalize on this ignorance by charging insane markups for bandwidth.