ISPs don't have the best profit margins, especially ones in competitive markets.. If the big players are selling DNS data, I guarantee you there are companies

ISPs don't have the best profit margins, especially ones in competitive markets.. If the big players are selling DNS data, I guarantee you there are companies out there approaching every other smaller ISP with a turnkey solution that makes it as easy as possible to do the same thing with some kind of revenue share model. Not a lot of businesses would turn down extra money like that, when they know their big competitors are doing the same thing. Unlike most ISPs, privacy and security are a core part of Cloudflare's brand and business model - at least at the moment - so it's in their own interest to actually not do this stuff. Only time will tell whether or not they pull a "don't don't be evil" on us, but that's a different conversation. :-)