Comment by pornel

Their business model is described in their S1 filing: https://www.sec.gov/Archives/edgar/data/1477333/000119312519...

* Cloudflare operates at a scale where its caching saves a lot of bandwidth, which saves ISPs money, which makes Cloudflare an attractive partner for peering and co-location.

* CDN is a platform on top of which Cloudflare can offer a lot of additional services that used to be expensive dedicated middleboxes.