Of course we were puzzled by CloudFlare's pricing structure. However, all of their advertising material kept reiterating that they were making money off low-tier customers by collecting lots of data required to properly serve their business and enterprise customers. So our sense of alarm and disbelief was somewhat suspended until CF contacted us about our bandwidth consumption, but even then we didn't realize how much trouble we were facing, as they first told us that a $1k subscription would do the trick.

Watching competing projects also added some degree of assurance. Without giving out any specific names, we are aware of a number of competing projects that even now keep heavily relying on CloudFlare (although I am obviously unaware of how much they pay), so we didn't consider it an abusive behavior. In contrast, we were also aware of at least one competitor that kept pushing a considerable portion of their uploads to imgur and basically parasitizing on them for a long time until imgur's abuse team finally took notice and brought down the hammer.