They have a free offering for anti-malware and anti-porn DNS server (1.1.1.2 and 1.1.1.3). Right now it's targeting for "families", but at some point they could easily monetize this especially to corporate networks.
And from a corporate perspective, historically no one ever got fired for using IBM. Who would you want running your Fortune 500 corporate CDN, a company that can handle 1.3T reqs/day or another CDN provider that's one-tenth the price but doesn't have the scale/reach of Cloudflare?